ST1300 - Only one Ground Point ?

[jfheath]

I'm just starting to investigate what I think may be the start of a ground issue.

I am aware of only one ground point on the ST1300 - the one that is on the cross member underneath the fuel tank.

Has anyone come across any others in their random probings of the ST1300 ?

I'm aware that the battery lead goes to the ground connector on the starter motor - and that this the only ground connection to/from the battery.
I'm also a way of the pink 24P multiway connector which conencts most of the ground leads together.

Is there any other connection to the frame anywhere (apart from odd components like the coill, spark plugs etc) ?

 

[afrymoyer]

I have a huge writeup over at ST-Riders about the 13's cheesy ground circuits and restoration.

To make a long story short, I bought an '03 last year really cheap and in beautiful condition. However, it would only start if you pushed in on the headlight housing. Other than that, the bike was dead. When the key was turned off, all the lights would stay on until the battery was disconnected. Turned out to be the yellow ground buss above the right headlight bulb. It was wedged in between the right windshield track and the fairing corner, corroded and burnt. I had it fixed in two days(without a service manual), but I made a huge "ground" improvement/modification along the way.

Looking at the complete ground circuit for the bike, that's the only place's I've found as you. Ground cable at the starter and the frame crossmember "main ground" under the tank. These are the only points. EVERYTHING electrical from the handle bars and forward, goes through the front yellow 14 pin buss connector, down through that white 24 pin connector, then to the main ground. All of it going through ONE 20 gauge green wire! Whoever designed this should be shot! Even if your bike has the updated "ground recall", it's still not enough.

I cut out the entire yellow ground buss, installed eyelet terminals and installed/mounted a marine ground Buss Bar above the right headlight bulb. I then ran a heavy duty black 12 gauge wire from the new buss bar to the main bike ground. I took apart the main bike ground, wire brushed the frame and terminals, dielectric pasted everything and reassembled. I also ran a 12G wire from the main bike ground directly to the negative post on the battery. The entire bike is now properly grounded, above and beyond...

While the bike was stripped, I dielectric pasted and Fluid Filmed EVERY electrical connector I could get my hands on. The bike has been flawless ever since.

I'll try to throw in some pix to give you an idea of what I did.

 

[Al Gully]

When the key was turned off, all the lights would stay on until the battery was disconnected. Turned out to be the yellow ground buss above the right headlight bulb. It was wedged in between the right windshield track and the fairing corner, corroded and burnt. I had it fixed in two days(without a service manual), but I made a huge "ground" improvement/modification along the way.

I cut out the entire yellow ground buss, installed eyelet terminals

Had the exact same problem and did the exact same thing you did, problem never resurfaced.

 

[Al Gully]

I'm just starting to investigate what I think may be the start of a ground issue.

Please share with us

 

[STRider]

I have a huge writeup over at ST-Riders about the 13's cheesy ground circuits and restoration.

Hey Adam!

Nothing to say about the ground points, but it's been a long while since I've seen my ole fellow STOCer poke his head up.

Tom

 

[afrymoyer]

Hey Adam!

Nothing to say about the ground points, but it's been a long while since I've seen my ole fellow STOCer poke his head up.

Tom

Hey Tom!

Ya, I stop in here and visit from time to time.

 

[jfheath]

Please share with us

There's nowt to share really. I have a niggle from a series of events.

1. Battery went flat in the car park when on holiday in June. Recovery chap jumped the battery , got the bike running no problem and checked that charge was going through the cable. I have no idea what this was, but its entirely possible that I left the ignition on for 10 minutes. Since I made my accessory feed from the battery go through one heavy duty connector, I just uncoupled it after every stop.

2. At home, I left everything plugged in for 3 weeks. The bike still started up, and when the battery tender was reapplied, it was a tad down and it needed just a short time to bring it up to full power - less than 30 minutes.

3. I noticed a feint flicker on the neutral light, which stopped when the engine was started.

I replaced the rear suspension with a brand new one. That involved removing the battery. I noted that both terminal were bent so the captive nut was not trapped. I tightened it as best I could.
But this can only have happened when the recovery chap tried to attach his really heavy duty crocodile clips.
I removed my Corbin dual Canyon seat and fitted my brand new, never been used, 9 year old original. But that meant moving the location of my InnovK3 Camera unit.
So I was checking things out and every now and then turned on the ignition for a few seconds. Headlights come on with ignitions, so these were brief checks.

4. My rear spoiler LED is wired with diodes and resistors to make it act as a tail stop light. ie slightly dimmer when riding, full brightness when braking. This time, when I pulled in the brake lever, instead of the LED lights going brighter, they turned off. They did this a few times. Started the engine - which fired up without problem. The tail lights worked OK. Checked again without the engine running. Same faulty result result.

5. I charged my old battery which had been replaced 2 years ago - because my horn wouldn't work when the bike was stationary. Fitted a new battery. Horn still wouldn't work when the bike is stationary with the new battery - so I have kept the battery on the tender for a few days every 2-3 weeks.

6. I decided that the bent battery terminals may be the issue. So I refitted the old battery. Flicker on neutral is better, but I think it is still there. Maybe its just the LED or bulb but it doesn't flicker when the engine is running. Rear spoiler light is behaving normally. Horn still doesn't sound when bike is stationary. It is a replacement horn Denali Sound Bomb Mini that doesn't draw too much power (5A stated which I didn't believe), so it is turned on by relay anyway. But the existing cable and fuse is well capable of supplying the current. The horn issue is the same with the OEM horn ie it won't sound unless the engine is running. Just a token 'Hmmph'.

7. All my accessory devices are supplied form one pair of leads with 30A cable direct from the battery to two relays - one of which comes on with accessories/ignition, the other with ignition. Nothing is attached to the standard harness.

8. I went out for a 230 mile ride on Sunday, with this niggle in my head. It is the only time I have ever felt the need to pack a fully charged battery. I didn't need it.

9. Satnav is showing spikes in speed on the trip logs. BlueTooth module to allow the Zumo XT to talk to my autocom drops its connection sometime during the start up process. I think when I start the engine. I've checked the voltage of the power feed, the continuity of the circuit and the resistance of each connection to its source. All OK.

But summat's up, somewhere. I am thinking earth problem, and that is where I will be looking next. But I haven't got any evidence to point me in any direction. Nothing else is faltering.

I've never had any problem with the multiway connector (That circuit diagram shows one for bk/wh power feeds and one for earth. It has the yellow one for the power feed. That is clearly wrong from @afrymoyer 's photo. I NEVER tap into the main harness for any of my own accessories. There is a limited supply from the quartet harness connectors - 5A here, 7A there. But generally, I leave that alone - except for heated grips which are designed to be plugged in there, and the trigger voltage to turn on my relays. So my 12v feed and return to earth do not add any load to any of the existing wiring.

 

[mjc506]

Would agree that it's worth looking at that front ground point. (Remove the dash and/or screen to get to it easier) I cut it off, a load of ring terminals, then a heavy cable to one of the screen mounting bolts I think, as a ground line (straight to the main ground point or battery would have been 'better' but would also mean another cable snaking through the bike getting in the way during maintenance). My left hand white multiway connector was fine, but the yellow ground block was burning internally, only visible with it disassembled. Failure symptoms for me was the bike not switching on with the ignition, but headlights and dash warning lights coming on dim, and not switching off with the key removed. Disconnecting the battery of course switched everything off, and the bike was 'normal', even starting up and running fine, until trying to operate anything that required any real power at the front end - headlights, indicators, electric screen.

Your "everything starts working when the engine's started" symptoms, however, remind me of something... My ignition switch is a bit glitchy. Sometimes, switching the bike to 'run' will get the fuel pump etc powering up and whirring, the dash backlight comes on, but the LCD display remains blank. Wiggling the key usually 'fixes' this. But also, starting the engine fixes it. I'm convinced that it's not the vibration shaking the key (it needs quite a bit of manual wiggling).

The ignition switch operates two 'switched live's plus the 'accessory' switched live when switched to run. Each of those 'ignition on' switched lives powers a separate set of fuses (I've forgotten which) but then once the engine is running/alternator spinning, I suspect the 'dead' half may be back-fed or something.

I don't understand why the ignition switch has two 'ignition' lines, and have not investigated properly yet... That's a job for the coming months... At the moment, I can't see any harm in tieing the two lines together somewhere, but I also assume Mother Honda had good reason for the complicated switches... I'm still going back and forth in my head with replacing the fuse/relay box entirely.

 

[jfheath]

I don't understand why the ignition switch has two 'ignition' lines, and have not investigated properly yet... That's a job for the coming months... At the moment, I can't see any harm in tieing the two lines together somewhere, but I also assume Mother Honda had good reason for the complicated switches... I'm still going back and forth in my head with replacing the fuse/relay box entirely.

I cannot get to my circuit diagrams at present but I have looked at that double switch before .

I would imagine that it is to do with the rating of the contacts. The ignition switch turns on power directly to circuits which carry some large current. The contacts will burn out or Weld themselves together if a higher current is switched on than that for which the contacts are rated.

I suspect that the two switches are simply a way of splitting the load.

If this is the case, it may be that joining the circuits will share the load between the two switches - in theory. But in practice, one set of contacts will always connect a tiny fraction before the other. They will carry the full load for a split second and that initial contact is when the spark damage is done.

 

[STRider]

... But in practice, one set of contacts will always connect a tiny fraction before the other. They will carry the full load for a split second and that initial contact is when the spark damage is done.

'Make before break' sort of thing... very common

 

[mjc506]

Yes, good point. I'd get the ignition switch to just power a suitably rated relay. There is potentially a lot of current going through those contacts in the bottom of the ignition barrel, just where moisture and much collect...

 

[jfheath]

Just been looking at the circuit diagram. The 30A fuse near the starter relay is connected to the battery and this provides power to the ignition switch at two inputs - Bat1 and Bat2. The ignition switch turns on and off 3 different outputs. Ign1, Ign2 and ACCessories. - As shown in this diagram.



For the UK ABS models,

This diagram means that when the key is in the ACC position (turned fully clockwise), BAT2 is connected to Acc. So power reaches only the hazard lights, and the accessory terminal in the quartet harness connector.

When the Key is in the Ignition position - 1 click clockwise, then BAT1 is connected to IG1 - That is fuses A B E
Also BAT2 is connected to Acc and IG2


Acc: Supplies Fuse F (10A) is the Hazard lights and Accessories. Turned on by connecting The Bat2 input to the Acc output.
Ig2: Supplies Fuse D (10A) Provides power to the kill switch which energises the Starter switch, the Bank Angle Sensor and the BAS relay trigger.
Ig1: Supplies power for 3 different fuses:
Fuse A (10A) ABS unit;
Fuse B (10A) (Vehicle speed sensor, Tail Light, Headlight aim motor, Position Lights, Ign Light, Console Lights
Fuse E (10A) Right Headlight - Via the starter button cut-out switch, and trigger for relay for left headlights.

Add the value of the fuses and you get 50A, but the total power draw must be less than 30A because it is all passes through the 30A fuse near the starter relay. It doesn't necessarily mean that there is spare capacity on each of those fuses. The 10A fuse is protecting the cable which will be capable of carrying at least 10A
Try to take advantage of the 20A capacity that seems to be available, and the 30A main fuse will blow !!

 

[mjc506]

Yeah, I figure all the "10A fuse" means is that the load draws close to or over 5A

Right, soo....

Flat battery while on holiday (possible ignition left on, or the Innovv not shutting down properly) but battery seeming OK (and replaced)
Slight flicker on neutral light (engine off, bike still?)
LED brake/tail lights acting weird (engine off)
Horn not working while engine off
Everything above working fine when the engine's running.
Spikes in speed on trip logs (presumably while the engine's running...?) Is this new, or just 'newly noticed'? 12V power shouldn't affect the Zumo, assuming it still has its internal battery in reasonable condition? What's this wired to?

You know what you're doing with a multimeter, so I'll assume the battery, charging system etc are all fine

If I've interpreted correctly, all the accessories (inc Zumo and Innovv) are powered straight from the battery, via a relay, which is switched using one of the 'quartet harness' switched live lines? (Which one? The 'accessory' switched live? Or there's a White/Green switched live on the bike side connector that only switches with ignition)

The neutral lamp is an LED, and it's series resistor is presumable selected to ensure long life (I don't have the specs of the LED used, but the resistor value is quite high, I think I measured <15mA last time I was in there). This means that the LED will be close to the 'knee' in its operating region, so small changes in voltage will be noticeable as small changes in light output (if the series resistor was smaller, and the current higher, the LED would be brighter, and in a flatter part of its curve, so the changes in brightness would be tiny and not noticeable). The strange thing is the 'flicker' - if the bike's just sat there, engine off, battery voltage should be falling quite slowly, not moving around much. A loose connector could obviously cause a flicker, but if the bike's sat still... Only other thing is something plugged in that's drawing power, and that power draw changing (resulting in a changing voltage drop, and a changing voltage at the neutral LED). The Zumo could cause that maybe, as could the Innovv, or maybe heated grips if they're cycling. Is the flicker regular, or random? Does unplugging the Zumo or Innovv 'fix' it? For an accessory wired direct to the battery to cause a flicker at the neutral LED would require quite some power draw I'd expect... Unlikely to be able to measure the changing voltage with a multimeter - digital too slow, analogue not sensitive enough. Don't suppose you have an oscilloscope?

LED brake/tail: I assume you have an LED strip or bulb or similar wired to the running light via a resistor to drop the voltage and brightness, plus another feed from the 'brake' line through a diode, bypassing the resistor?


Are the stock bulbs still filament, or LED? I must admit, if this is how they're wired, the only reason I can think for them to switch off when you apply the brake is if the additional load of the stock brake light bulbs pulls both 'brake' and 'running' voltages low enough that the LEDs don't illuminate (and with the engine running, voltage is high enough) but this is clutching at straws really... Or the diode has failed short circuit, but this should be fairly obvious

Horn: These are quite voltage sensitive (you have the stock 'pancake' horn?). Each one is a little different, but the ones I have here stop working at somewhere between 9 and 11V. They need enough 'oomphf' to push the coil far enough to start oscillating, once they're sounding the voltage can drop quite a bit lower before they die.

The Horn and brake lights are both powered from fuse C (via the main stop relay) on a White/Green wire, which also goes to one of the connections on the quartet harness connector. (There are two White/Greens on the quartet connector (assuming my diagram is correct)?! The other is powered by fuse J - battery clock backup, permanent live)

Hmm. Both fuses C and J (plus a few others) are powered from the battery via main fuse B (65A fusible link), and also direct from the alternator. Could main fuse B have a poor connection, dropping voltage from the battery until the engine starts and the alternator takes over? If it's blown completely, the bike would be dead (fuse L - FI, coils, fuel pump).

Are you able to measure the voltage on that White/Green line (to battery negative) with the bike off (should be 0V), on (should be battery voltage), on with brake lamps illuminated, and then engine running? Ideally also the same at the battery terminals too, but hopefully by this point you'll have spotted something...

 

[jfheath]

Thanks for all of the comments @mjc506 . Wow.

I'll answer some in brief - as today I went out with the intention of investigating the 3 main earth connections. And failed. I hadn't realised that I cannot get to the cross beam spar conenctor under the rear end of the tank without taking the tank off - so that will have to wait - so there was no point in checking the connection with the starter motor either.

So instead, I measured the resistance between the battery terminal and the exposed thread on the two tank mounting holes. 0.1-0.2 Ohms. This was pressing down on the top of the negative battery lead terminal on top of the battery.
So that seems OK.

The earth passes the load/current test as the starter motor has no trouble starting.

I checked that the green neutral ligth was flickering when I turned on the ignition. It was. And it stopped flickering when the engine was running and started flickering when I turned it off. It's not an on/off flicker. Its a rapid change of brightness flicker.

I have not been able to repeat the behaviour of the spoiler tail light when the brake lever was pulled in. Ebven disturbing the unit that allows this to happen.

Here's my installation. Article [13] - ST1300 - Spoiler fitting | ST1300 Articles | Page 3 | ST-Owners.com

My accessory installation is documented here - except I have redone it to provide different power in different places - but you get the general idea. All power comes from the battery and is split between two relays. The main power feed has a 30A fuse attached near to the 65A fuse on top of the battery. It has a twin connector under the seat to make it simple to cut off the power supply to the accessories. I need to take a look at where I have taken the heated grip power from. I can't tell at the moment.

Fuses are all OK. But I havn't taken them out recently to check for oxidation. Ditto the main 65A fuse. That is worth a look as I take my power from the alternator side of the fuse rather than direct from the battery terminal - this is so that my accessories don't overload the 65A fuse.

Today I removed the battery, cleaned up the battery 'posts'. I cleaned up the battery wire terminals, and straightened them, and cleaned up my accessory eartth terminal.
Before doing this, the neutral light flickered. After cleaning up, it didn't - but the battery had been on charge in the meantime. I'll try it again in a couple of days.

The Innov is disconnected for all of this. The Innov has to have constant power so that it can close down the recorded files after the ignition has turned off. The new version of the firmware doesn't put as much drainon the battery as the old one - nevertheless, it has failed to protect the battery drain just once. Like many electronic gadgets, if you trun it off before it has properly started up, it doesn't seem to recognise that it has been turned off again. So I now have a connector under the seat which breaks the power supply. I use the same connector to power my air compressor and my battery tender !. By the time I get the seat off, it will have shut down the recording anyway. But I've deliebrately left it connected during a Covid Summer for weeks on end and the bike started just fine.

I'm also replacing the battery on Wednesday - I'm trying to get a way to find out the date of the new one. I've been given a number at Yuasa to call - so I'll do that before I walk out of the shop with it.

Battery is charging from the alternator OK. Heated grips would flash and swithch off if the alternator wasn't producing enough power.

The spiking on the satnav isn't new, but I have yet to establish when it started. Looking at my satnav logs, it has got progressively worse - but there have been a number of satnavs over this time, and it seems to be only the XT - but I have had a replacement.... so I still have to pin this down - and for that, I need to take the screen and front cowl off to get at the connectors to check that these aren't the cause. That will have to wait.

The Horn has failed to sound for a good few years. Originally I had the standard ST1300 horn - which refused to sound. It passes the MOT test, because it says in the testers manual to check it with the engine running if it fails to sound without. The horn is now a Denali Sound Bomb Mini. Draws 5A, which is within the scope of the fuse and wiring. Nvertheless it gets its power from my accessory line through a relay, which is activated by the wires which used to go to the old horn. Just becasue the wires will carry that current, doesn't mean that the switch is good enought to switch it. I suspect it will be, but I didn't want to assume.

So - possibly a bit of progress today -with nice shiny terminals (which I forgot to grease). I'll check the fuse contacts next as you suggest. I'm thinking of getting a new battery earth lead and taking it straight to the earth point under the rear of the tank.

And when I get the nose off again, I'll inspect the multiway harnesses.

 

[mjc506]

Today I removed the battery, cleaned up the battery 'posts'. I cleaned up the battery wire terminals, and straightened them, and cleaned up my accessory eartth terminal.
Before doing this, the neutral light flickered. After cleaning up, it didn't - but the battery had been on charge in the meantime. I'll try it again in a couple of days.

Sounds promising

Yes, the 'change in brightness' flickering is what I assumed to be honest. I was happy to blame the Innov (writing to disk will draw a little extra power) but if it's unplugged... The Zumo may have a strange charging circuit? I'd expect some sort of SMPS to keep the battery charged, but it could be anything I guess. But if it's something like that, that more points to a power problem - nothing should really be able to draw enough amps to affect voltage enough with good battery connections and a good battery.

Hopefully you find 'the smoking gun', always frustrating when a problem just goes away... never know if it might come back again...

0.1 - 0.2ohms between battery negative and frame ground is probably fine, but probably lower than most multimeters can read. Bear in mind that with (say) 30Amps flowing through a 0.1ohm resistance, that's still a 3V voltage drop (a 'better' test would be measuring the voltage between battery negative and some ground line up front, with all the headlights etc on (max electrical load). Hopefully giving you a fraction of a volt voltage drop. Could do the same between battery positive and a similar power line.

 

[jfheath]

Thanks Matt.

The wiring and cradle for the Satnav is in place, but the Zumo itself stays in the house when I'm not riding.

The resistance 'test' was really only to check for a ridiculously bad connection. Most short lengths of brand new wire show a minimal resistance so I knew that the obtaining a low reading was only useful in telling me I didn't have a high reading ! I also know that a low reading doesn't mean that the ability to conduct when under a heavy load is confirmed.

Its round about this point that my practical electronic know-how begins to crumble like verdigris. So thanks for the suggestion to measure voltage between two different points on the same earth. I do understand how that works - but I would never have thought of doing that. That must be standard practice - similar idea to measuring high current flow across a 'shunt'.

That will have to be in short bursts of activity. As you know, headlights come on with ignition in the UK, and they can flatten the battery in a very short space of time.

 

[V4 Rider]

Easy to temporarily disable the headlights by removing the relay.

Then you can have much longer to do testing.

Measuring small values with multimeters is drought with problems. Look at the accuracy specification do the maths and you will see the problem.

The issue is we see a 4 digit resolution and assume it means the last digit is accurate. Unless you are using an expensive calibrated meter it is not.

Checking for earth impedances is best done with a specialised meter.

Measuring voltage is more accurate as value is reasonable on a 20V scale.

Leave one probe on battery negative and work along the positive and negative circuits checking voltages.

 

[mjc506]

Exactly like measuring current across a shunt, except in this case you're looking at resistance from a known voltage and estimated current

Yeah, pulling the headlight relay will give you longer testing time, but less load to help find issues. Do you have a handy car battery? No harm in 'jumping' that across the ST battery while you're checking voltages.

Ok, so not the Zumo (from memory, the wiring and cradle just bring 12V to the Zumo, all the DC-DC conversion is done inside the unit I think), and not the Innov causing the flickering neutral lamp, but that maybe stopped now anyway. The only other 'active' loads on the bike (sat still, engine off) would be the ECU and dashboard I think? Might have to have a play and measure current draw on mine and see what happens! Just out of interest, not much can be done about it...

 

[jfheath]

I'm well familiar with the 'false accuracy' attributed to digital displays @V4 Rider - but thanks for the comment, I might not have been aware.

Today I didn't do much apart from repair the back wall of the garage - before the new houses there claim the land, built the fence and I can no longer get to it !
But I did turn on the ignition and wacth the light. There was ONE dim of the bulb - which I guess was something else turning on. And then it was steady. I tried it a few times with the same result. Then I started the engine just to take some power out of the battery - and I'll leave it until tomorrow now, let it sit without doing anything.

Tomorrow I'll do the earth voltage check in a few places. See how much voltage is going through the frame to the earth lead with headlights blaring. Actually, I can do it with the pass main beam on - which turns on all 4 filaments of the headlight.

I'm OK for time. I'm not going anywhere any time soon. Its pretty cold, wild, blowy up here in the Pennines. They are only small hills by continental standards, but with maritime air, they sure make a difference to the weather and temperature. But if there is the opportunity to go out for a day, I want to be able to take it - albeit with my second battery charged and ready to substitute.

I want to check the earth terminal on the starter motor, but am reluctant to disturb it - if it sheers off ..... I'll do the earth voltage check first.

 

[afrymoyer]

I got to thinking about this some more...

While I was troubleshooting my problem, I ran an alligator clipped jumper wire from battery negative, to the horn ground (green wire) while the ground was still attached to the horn. The bike came alive and everything worked perfectly. This grounded the back side of the yellow 14 pin ground buss. Plus, the horn started working too. This is what led me back up into the front ground buss.

It sounds like you're getting closer to a solution, just by cleaning up the negative terminal on the battery. Good move by replacing the battery too. Don't forget to take a magic marker and write the install date on it for "the next time".

In my opinion, any resistance in the ground/earth circuits isn't good. Your meter should read "0". 2 tenth's is too much. I'd start running test ground jumpers to zero in on the crap connector, wire or circuit. Jump the front ground buss, the 24 pin connector and the main ground under the tank. All you need is alligator clipped wire and a paper clip.