Ad.Hom goes huntin' (for gremlins)

[ad.hom]

Figured I'd start a thread of my own to chronicle this - I'll come back & update with progress & pics, though it might be a slow project. Partly this thread is to help me document things that I've looked at along the way.

Right now, the bike is laid up with all the plastics off (incl. headlight assembly) and it's been this way for about a week now. I've just not had the time to look at it. Today was different, so today I started to poke it with the multi-meter before life got in the way again.

Re-cap of the problems:
- LH headlight ground connector has melted (been riding around for a few weeks with it unplugged, but conscious that will spread the problem elsewhere & I'm needing light more now, so the bike is parked up until I cure it).
- Intermittently, the windscreen up limit switch hasn't worked, though occasionally it's been fine.
- once or twice, on very wet days, the neutral light has illuminated while clearly not in neutral (being ridden in 4th for example).

Wiring diagram from this thread has been printed: https://www.st-owners.com/forums/threads/st1300-wiring-schematic.90873/

Today, I got as far as:
- checking the yellow ground connector behind the RH headlight (fine)
- checking the earth connection from the LH headlight through to the frame "bridge" under the tank (fine)
- checking operation of the up limit switch (fine). Since this wasn't a problem I couldn't swap the upper/lower relays to test anything
- checked the headlight aim motor & RH headlight connector for signs of melting (fine),
- checked the horn connections for signs of melting (fine),
- noted that the "options connector" is pretty gummed up (black tar like substance). Tried to find my contact cleaner spray to no avail. Will test the LH headlight to Options connector ground path when that's cleaned up.
- checked LH headlight to side stand switch ground path for signs of melting & continuity (fine)
- checked radiator fan connectors for signs of melting (fine)
- checked fuel pump connector for signs of melting (fine)
- checked all cabling for signs of chaffing/rubbing on frame etc (nothing evident, haven't unwrapped anything)
- checked fusebox for signs of water ingress (fine).

At this point, the heavens opened up, and the bike is parked outside, so all electrical works are halted & the bike is covered up. Looks like only the options connector & main harness connector on the left side of the bike - both being heavily gummed up - need to be cleaned / checked.

As I've looked at the wiring diagram this evening, I think I've identified the root cause. A previous owner of my bike fitted non-weather-proofed USB connectors to the dash (on top of the dash) and wired it to take power from the main connector on the back of the clocks (positive from cluster illumination, negative on chassis ground). Looking at the diagram, I've learnt that this chassis ground is shared with the headlights (and headlight motor). I'm aware in the past that I've been charging my phone in the USB connection while riding in the rain a few times. I speculate that the increased load on the circuit (charging my phone + water) has fried the LH headlight connector ground (given I can't see anything else really wrong). This same ground connection is also shared by the up/down limit relays on the windscreen (and the options connector).

So, the plan of attack when I get the time:
- ask you guys if you have any other opinions on things to check/considerations in general
- find switch cleaner spray
- clean & check the main harness & options connectors on the left of the bike
- replace the H4 connectors (both) with new pigtailed connectors
- wire secondary earth point from the H4 pigtails to the headlight subframe to help mitigate the load issues (seems to be an intermittently reported problem across a number of owners)
- wire in the busboard fuses that I recently purchased (need to get a 100A 12V relay first)
- wire USB connectors to come from the busboard
- fit & wire in the stebel horn that arrived this week - will be connected to the busboard with a relay on the original loom
- run wires for future additional lighting (front & rear) with waterproofed connectors.

Should anyone have any thoughts on what to look for, thanks in advance, I'm all ears.

 

[Larry Fine]

I'm aware in the past that I've been charging my phone in the USB connection while riding in the rain a few times. I speculate that the increased load on the circuit (charging my phone + water) has fried the LH headlight connector ground (given I can't see anything else really wrong). This same ground connection is also shared by the up/down limit relays on the windscreen (and the options connector).

It is extremely unlikely that water conducts enough current to affect a connection that way.

 

[ad.hom]

It is extremely unlikely that water conducts enough current to affect a connection that way.

As above, I'm open to suggestions.

Given the number of people reporting the LH headlight connector melted is non zero, it is surely plausible that the circuit is near the designed load limit for the connector - and as such might not take too much extra to cause damage without blowing the fuse.

I haven't calculated the draw my phone causes, let alone added the fact that water was inside the female USB connector. It's simply a speculation at this point.

 

[Nashcat]

I would do the ground wire bypass, around the 26? pin connector, under the left fairing. There’s a thread here somewhere, with pictures where I did the bypass on Fali’s (Indian Express) bike. The bypass also fixed Seawalker’s bike, then I did the fix on my 1300, before any problems showed. Also on these 3 bikes, I soldered a wire to the connecting bar in the yellow connector, behind the right headlamp, and ran that extra wire to a frame ground. Both will be quick and easy, if you already have the plastic off.

John

 

[ad.hom]

Thanks John,

Assuming that I still can't find any more problems the next time I attack the bike, I'm planning on adding a ground from the headlights (both sides) to the front subframe.

Good call on also bypassing the pin from the port side connector (currently gummed up).

I'll have a search for the thread you mention...

 

[spiderman302]

LH headlight ground connector has melted

If it is the connection at the headlight, both the low connector and the common connector have the same current (5 amps). There is 65 watts of heat generated by the bulb. If only the common has melted then it was loose or corroded. the heat from the one bad contact plus the heat of the bulb will melt the plastic. Replacing the headlight connector will fix that problem.

The ground wire through the 26 pin connector is highly stressed since it is carrying 15+ amps from all the front lights and console. Adding the extra ground bypass from the Headlight connectors to the frame ( or better straight to the battery ) would be a good improvement.

When you clean these connections also make sure they are tight.

 

[SupraSabre]

Electrical Gremlins and I just don't get along!

Good luck on your quest!

 

[Nashcat]

I found Fali’s post of the repair.

Yesterday I rode over to John's (Nashcat) to take advantage of his lift and soldering skills. We first checked the 14 pin yellow plug (right side). Everything appeared to be normal. Next we checked the 24 pin plug on the left side (as in riding position) and found the ground wire burned, insulation melted off and wire exposed.
.
The plug terminals were cleaned and a jumper with a quick connect/disconnect and pig tail with ring was soldered to the affected ground wire. The end with the terminal ring was ground to the frame just above the plug. (Don't let all the multicolored cruise control wires confuse you)


For extra insurance a 16 ga. ground was soldered to the bottom of the yellow plug where all the ground wires are soldered together and the terminal ring was attached to the frame at the point where one of the nose cowling supports is bolted to the frame.




Since my return from Maine, the bike has started every time I tried but the clock would reset, the trip odometer both A And B would reset to zero, and the bright lights would not turn off or only one light would dim. I haven't ridden it anywhere outside the neighborhood until I rode it to John's place 60 miles away. The symptoms of the bike not starting and lights staying on never repeated themselves since I have been back but I suspect it was only a matter of time, somewhere down the road if it had not been repaired.

All the crazy stuff that was happening with my dash board display has stopped and head lights appear to be much brighter. I feel confident we have made a good repair and I can once again ride far away from home. Hope this makes it a little easier for the next person this happens to.
Thanks for all the great advice and troubleshooting. This repair did not take long because of all the legwork that has already been done to solve this issue.

 

[ad.hom]

Thanks for the replies folks...

If only the common has melted then it was loose or corroded. the heat from the one bad contact plus the heat of the bulb will melt the plastic. Replacing the headlight connector will fix that problem.

Yep, only the ground connector has melted, and it's entirely plausible that it was loose & causing slight arcing. The plug didn't feel loose when I removed it, but that could have been the other 2 pins that were tight.

I'm going to add a link to the schematics posted by SpikingJC.
...
You aren't that local to me, are you ?

Thanks for the schematics, infinitely more useful than the one I linked because the colour labels are clear. Even if there's slight colour changes for my 02, having them clearly labelled makes it easy to follow (speculation on my part that there could be differences since the diagram says 03+).

I'm not too close to you, North Wales. I'm better with a soldering iron than a spanner though, and I get by with spanners. My main problem is time, though I'm hoping to find a spare hour this evening to re-check my findings (from the school of thought "measure twice...")

I found Fali’s post of the repair.

Thank you for the pictures. The connectors on my bike aren't that bad, though I don't have the problems reported by Fali either. Maybe I just happened to catch it before it got worse.

 

[ad.hom]

I'm confused with one symptom that you described - the neutral light coming on when it shouldn't.

Thanks for the pointers so far. The neutral light I'm not concerned about - it happened once last winter, going over rough tarmac in the wet. It later extinguished itself on the same ride (gradually dimmed).

I commented in a thread about that at the time, and the thinking was basically water + salt (winter gritting) might have gotten in somewhere, and the vibrations from rough surface helped it along the way. The gradual fade was speculated as drying out due to engine heat.

I checked the fuse box for signs of water ingress at the time, and I've not seen it since despite riding in truly biblical stoms. No ham in having a look again while I have the bike in bits though.

Hoping to get a little time to poke it this evening, retracing my steps with a volt drop test at various points. Currently posting from my new commute ride - merseyrail

 

[ad.hom]

Managed to snap a few pics before losing light... also going to pick up an outdoor workshop light so I might get more time to look at this.... But still, pics of the current state....

 

[ad.hom]

Sorry, its not an answer, but I hope the information helps.

No problem, I wasn't expecting an answer (I know that's already difficult without the bike present). I appreciate the thoughts on what to look for.

To address some of the questions/comments...

The bulbs being standard or not, I've no clue honestly right now, easy to check though given that the headlight assembly is in the shed...

The LH H4 connector, to me, looks like the back of the connector started to go first, whereas I'd expect the front to melt if the cause was heat from the bulb. It's only near the ground terminal that has any damage too, and the wire looks a little burnt just before the spade terminal. As you say, hard to observe in the pics.

Probably worth pointing out that the screen stopped moving upwards (intermittently) after I unplugged the LH headlight. I can't see any damage on those wires, but it leads me to suspect that there's still a problem somewhere. When I remove the headlight assembly (and aim motor), the screen up/down had no problems at all.

The yellow 9P ground connector looks immaculate, and the grime on the 24P I expected was pickup from the grease. I included the pic more to show it doesn't show signs of damage, though I'll clean it up to make things easier to probe, and reapply grease before putting it back together.

I don't remember seeing a purple connector, but I'll keep an eye out for it & keep you (and others) updated.

This evening, I did test resistance in various earth paths. The largest, as expected, was from the damaged H4 ground pin to the green earth cable near the pillion seat, and that was 0.9ohm (so, likely just length of cabling + frame resistance). Everything on the front of the bike to front subframe, ignition barrel etc, was less than that.

Also of note I guess, when the LH headlight was connected but not working, the high beam dash indicator was illuminated (apparently common with this issue) and putting my hand down to move the wiring usually cured it, making the headlight work. I suppose this lends credence to it possibly being a loose spade terminal inside the H4 connector. At no point did either the PASS switch or full beams blow any fuses (but I've not checked them to see the rating yet either).

Part of this work will probably see me running a 5AWG cable from the back of the bike up to the front anyway, so I'll be checking/cleaning/tightening all the earth points as I get chance.

 

[ad.hom]

So, I found time to poke the bike again today... having rerun through the entirety of this thread (thanks all involved)... I've found nothing wrong bar the LH H4 being melted (and the ground wire burnt at both LH and RH connectors, no damage to the RH connector though).

Since the wife has just made a bacon butty & opened a beer, I figured this was a good time to pause.

Also, the spade on the back of the LH headlight was burnt on the ground connection.

So, I've ripped out both the existing H4 connectors & replaced them. I've also wired them both an extra ground to the front subframe. I've also run a secondary ground from the front subframe to the rear subframe, and from there to the battery.

Hopefully, on the assumption that it was a loose cable/water issue, that should resolve it.

I'm in the middle of adding a new fuse block for the horn installation. I've already setup the 100A breaker and a 100A relay to switch on with ignition. Next up is hooking the breaker to the battery & wiring for the horn, then mount the horn & test everything. The horn is apparently capable of drawing 30A, so that'll get a 30A fuse in the block.

Then I'll run another wire from the fuse block to the front for future lighting, and another for the USB & accessories branch.

Once all retested ok, I'll solder all the connections, heat shrink them & tape what I need to tape. Then I'll start the fun of putting the Tupperware on again... As I'm doing that, I'll pop the new H4 bulb in to replace the old.

 

[Upt' North]

So, I found time to poke the bike again today... having rerun through the entirety of this thread (thanks all involved)... I've found nothing wrong bar the LH H4 being melted (and the ground wire burnt at both LH and RH connectors, no damage to the RH connector though).

Since the wife has just made a bacon butty & opened a beer, I figured this was a good time to pause.

Also, the spade on the back of the LH headlight was burnt on the ground connection.

So, I've ripped out both the existing H4 connectors & replaced them. I've also wired them both an extra ground to the front subframe. I've also run a secondary ground from the front subframe to the rear subframe, and from there to the battery.

Hopefully, on the assumption that it was a loose cable/water issue, that should resolve it.

I'm in the middle of adding a new fuse block for the horn installation. I've already setup the 100A breaker and a 100A relay to switch on with ignition. Next up is hooking the breaker to the battery & wiring for the horn, then mount the horn & test everything. The horn is apparently capable of drawing 30A, so that'll get a 30A fuse in the block.

Then I'll run another wire from the fuse block to the front for future lighting, and another for the USB & accessories branch.

Once all retested ok, I'll solder all the connections, heat shrink them & tape what I need to tape. Then I'll start the fun of putting the Tupperware on again... As I'm doing that, I'll pop the new H4 bulb in to replace the old.

Can you please tell your SO to put down her beer and bacon butty and give you a chuck me duck.
Cheeky mare! .
Upt'North.

 

[ad.hom]

Can you please tell your SO to put down her beer and bacon butty and give you a chuck me duck.
Cheeky mare! .
Upt'North.

To be fair, they were for me, not her... Did i mention we've also agreed sale on the house so are traipsing around having viewings on somewhere else at the same time as I'm working on the bike...

Anyhow, after a few pit stops, end of play today... Still have the horn to finish but that'll be tomorrow (cordless drill battery is flat).

Some pics of the work so far...

(Ignore the tape, they are soldered, greased & heat shrink wrapped before the tape goes on...).

 

[ad.hom]

Idiot moment as I'm putting the bike together again... can't pay my hands on the parking/side light bulbs.

Don't suppose anyone can tell me what bulb it is? Wedge shape connector, 5W... I'm seeing reference to 194 in some places, but calling local shops they're rarer than hen's teeth...

Thanks in advance...

 

[ad.hom]

Conclusion here...

It was 194 w5w bulbs for the sidelights. The 6k ones I've fitted are almost as bright as the headlights.

New earth wiring added, and so far (touch wood), no issues.