ST1100 ABSII Code 7 - Faulty Power Circuit

[Larry Fine]

UP, You may have good voltage, but do you have good grounds?

When the battery is ruled out as suspect, you can use what's called "fall of potential" (fancy term for voltage drop) testing by connecting a voltmeter or tester's red probe to the battery positive terminal, and using the black probe to the point suspected of having too little voltage.

This also works to find poor connections on ground current pathways. Connect the meter's black probe to the battery negative terminal, and use the red probe to see how much voltage is being dropped between the battery and the point that should be at ground potential.

The voltage that is lost along the way will be indicated on the meter; obviously, less is better. A test light will also work, but bulb or LED brightness is not as sensitive. Ideally, there should never be enough voltage drop between any two points of the same circuit pathway to light a bulb.

 

[Uncle Phil]

Well, got a bit sidetracked on this project as one of my other ladies got a leaking clutch slave cylinder. I got it replaced yesterday using a Oberon slave cylinder. Got to finish testing and buttoning her up before I get back to this one.
But all the advice is really appreciated and will be put to use shortly.
BTW, any remember where the main 'ground' connection is on the ST1100 ( it would save me from having to research it)?

 

[ardykay54]

BTW, any remember where the main 'ground' connection is on the ST1100

Where the tires touch the road??!!

 

[kiltman]

BTW, any remember where the main 'ground' connection is on the ST1100 ( it would save me from having to research it)?

It will be connected via the folding handle bolts or on the left pannier rail

 

[John OoSTerhuis]

It’s left side on the engine below the engine guard/tipover bar, near the starter motor cable.

 

[Uncle Phil]

It’s left side on the engine below the engine guard/tipover bar, near the starter motor cable.

IIRC, somewhat near the oil filter.

 

[Uncle Phil]

I did get a chance to crank her up this morning (as I was leaving for work) and check the voltage across the battery terminals - 14.5 according to the meter.
Next step will be to check the condition of the grounds and then 'go fishing' for another problem if that's not it.

 

[Uncle Phil]

Though they looked 'good', I cleaned the main ground and the one near the grab handle - still no joy.
Installed another 'new' brain today and hope to test it tomorrow.
The manual says a 7 error has one of 3 causes - bad alternator, bad 'brain' or the wiring harness.
Alternator output appears to be 'in spec' so I hope the 'brain transplant' fixes it.
If it is buried in the wiring harness, that is too much sugar for a nickel to fix.

 

[Uncle Phil]

Different Brain, proven battery off a working ABSII ST1100 - still no joy.
At this point the ABS lights come on solid.
I've cleared the codes and all I get now is long flashes.

Mr. Heath - How fast does the front wheel have to be spinning to get the ABS light to flash?
I can get the rear to cause the flash by putting it in gear.
But I cannot get the front one to flash and I am wondering if I am not spinning it enough or I have a bad front sensor.

 

[Uncle Phil]

I just replaced the front sensor (Thank you Mr. Heath for your well documented ASB travails) and rode it down my driveway.
The ABS lights went out as they should.
Then I stopped, turned off the bike, turned her back on, took off and the ABS lights went out again.
I think that we can 'add' to the Honda 'manual' that a bad sensor can cause the system to throw a CODE 7 - Faulty Power.

 

[jfheath]

Well done UP !

For anyone looking in that wondered what Phil was on about in the posts above - I wasn't ignoring him - we got into a private discussion. The flashes the UP mentioned in the last but one post . These were not the fault code flashes, but what appear to be diagnostic flashes.

If you obtain the fault codes, clear them and then do not turn the ignition off, then when you spin the wheels, the ABS light will flash as the wheel turns - if the sensor is working. No flashes appears to mean faulty sensor. This is not documented that I have seen. I came across this by accident, and it worked for me. UP is the third that I know of that has used it to establish a fault.

So it seems to work.

John

 

[Uncle Phil]

I also noticed that when you install the front ABS sensor you need to be really careful that you have clearance and it does not rub on the ABS ring.
Don't ask me how I know that!
Though it appears to have no 'adjustment' at first glance, there is a wee bit of up and down once you fuss with it a bit.

 

[Ron]

I also noticed that when you install the front ABS sensor you need to be really careful that you have clearance and it does not rub on the ABS ring.
Don't ask me how I know that!
Though it appears to have no 'adjustment' at first glance, there is a wee bit of up and down once you fuss with it a bit.

At one time, I had an ABS II with shims on the sensor. The shim is item #24, shown below as not available. It goes between #6 and #23. I think a couple washers would work. From what I have heard, the sensor can detect the high/low trigger from a greater distance than Honda suggest. Back when I was young and dumb, I also buzzed a groove in the front sensor about 3/32" (.100") deep. Now, I'm merely dumb. I didn't notice it until the next tire or brake swap. The sensor was working. I shimmed it out to a more correct distance.

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[Uncle Phil]

Never noticed that before - the washer idea should work fine.
What I do now is install the sensor before I install the brake pads and do a 'spin' test to make sure there is no contact.

 

[Uncle Phil]

Knock on wood (normally using my head for that ) the ABS has behaving itself for a while.
The front sensor - which had a groove in it - was probably the problem all along but manifested itself as 'other' problems.