Everything was going very well with my Focus until the top of my ABS pump had an electrical melt-down!! I managed to get a salvage Pump with identical markings along with the plug which I carefully crimped onto the loom.
It did not really surprise me that the ABS lights are still on, and its not working.
I took it to a ford garage who tell me that their computer tells them that the module is faulty. This might be the case, but the supplier of the secondhand part are convinced it worked. (they have offered money back, and seem very resonable)
The ford garage dont really want to look further. maybe I need to get the osciliscope out!!
Can anyone point me to a wiring diagram?
will this unit reset itself, or will it need resetting at the garage?
apart from the 4 sensors, what else could be at fault??
since wires were melted (mainly the thick red one), it is quite possible that there are problems elsewhere. Two fuses had blown, so I guess the first thing to confirm is that there is voltage to the unit. Hence a wiring diagram might be my first step.
Any help gratefully received.
Edited by Dynamic Dave on 05/03/2008 at 22:01
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Melted wires?? All the feeds to the ABS are fused - the largest being 30A; so how did the wires melt? The two reds are perm lives and the green/yellow is the ignition feed.
Is there more to this than it appears? It's not as if the current runs for more than a few seconds?
Let's start with the year and does it have TC and ESP? What exact codes did the dealer find?
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The burning was local to the top of the connector, and the fattest red wire. i.e. it could have been the wire loose in the connector. It happened after about 3 mins of driving in town.
It must have TC because one of the lights shows a spinning wheel, but I doubt if it has ESP.
Its a low-spec estate.
I guess I should first check the 2 lives and the ignition feed.
The fairly friendly guy at the garage simply said it all pointed to the module itself. I could get back to him and ask if there were any codes.
Many thanks for your help. I have been worried that this could right-off a good car.
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That's the surprise; there should be no current flow on that wire unless the ABS is operating - so what burned it??
What year is it? TDDi or TDCi?
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That is a very good point, the unit certainly was not operating.
Firstly its 2001 {now added to header}, standard estate 1.8TD fairly basic, steel wheels etc.
I have just had a closer look at the damage. The meltdown epicentre seems to be lower in the plastic just below the plug (down to level with the top surface of the AL block. The two current-carrying wires closest to the AL block are heavily burnt at the connectors, but the cable seems 1" or so away from the unit.
I'll look for voltage on the cables you mentioned.
If it were an internal short, then one might expect the fuse to blow before the burning. That is what fuses are for isnt it? Both fuses were gone when I first looked.
Its certainly a puzzle
thanks for your thoughts
Edited by Dynamic Dave on 05/03/2008 at 22:01
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Further to my last message; I have done a few tests.
I have checked the wires that you suggested Screwloose. two reds have 12v, thick green/yellow has about 10.7v which I guess is the regulated ignition supply. thin green/yellow has 11.7v
there are a pair of black/green which I assume can be either way around.
I thought I could easily un-plug a wheel sensor. is there a check for these? what are they?
The garage\'s computer apparently only reported that the module was at fault. (I have been assured that this it was a good one, and it has all identical markings.)
I guess that anything attached to the module could have been subject to 12v. I wonder if this could have damaged anything else.
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There should only be one green/yellow; the other one is yellow/green.
The speed sensors aren\'t going to burn the main feeds; so the only possibility is a big short in the ECU - very odd.
It\'s doubtful if there is a speed sensor signal [10v square wave across the wires - connected] if the module is U/S; but check the black/yellow is a good earth.
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I have had the ossiloscope out, and found the following;
12v present on both reds.
zero volts on black/yellow (is that a good enough earth test?? should i try passing some current somehow?)
otherwise nothing very interesting; no AC on any pins, but a 2 second 9v (ish) pulse on one of the black/green. various static DC voltages on other pins.
I then looked at the front sensors. they have 12v across the white and yellow ,. and white to yell/red (on off side)
this 12v drops to about 3.5v when the sensor is re-plugged in.
no AC signal seen. no change when the wheel is rotated.
If i swap the two whites by the pump plug, then I'm getting 12v across the yellow and either white, and the yellow/red, and either white (with sensor plugged in). Its getting a little confusing.
This implies that the orientation of the whites is important.
further info; pump number 98AG-2C285-AC.
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I couldn't reconcile all of those wires; but it appears that the [Hall] sensors are not active; perhaps unsurprising if the module is in disabled mode - it wouldn't need to know the speed if it's not going to use it.
I normally use a live-fed bulb test-lamp for earth tests - much easier.
I still see two questions here; one, why was excess current flowing on the red wires - and two, what code[s] are stored in this module.
If code retrieval is impossible; then I can only suggest sending the ECU for testing to see if that gives any clue to what's going on.
Edited by Screwloose on 07/03/2008 at 12:48
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I just spoke to the garage man. He said that the unit was not recognised, so no codes could be got. I guess I should send this module back since its under warranty, and I'll just send for a replacement.
My only worry is that there is some sort of problem between the unit, and the computer.
Can you think of anything that could go wrong between unit and computer??
I carefully crimped on a new plug. my only concerns were the wires of the same colour ( there are two whites, and two black/greens) so I assume these can go either way around.
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After 2 months with a broken leg!, i need to get back and fix my Focus.
I now have a reconditioned ABS pump unit. Fitted it and bled the system. Switched on, and ABS light and TC light remains on.
The previous ABS pump was secondhand, and gave the same symptoms with the lights. and the garage told me that their computer said 'unit not recognised' . My guess is that if i take it along the the garage, the same message will be seen.
I have checked the cables,- Two reds are 12v, green/yellow is 12v from ignition. earth is good.
is there anything you can think of that I should look into before i take it back to the garage.
Is it important for it to be bled correctly for it to work?
any thoughts appreciated,
many thanks
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The two white wires are not interchangable; one goes to the diagnostic socket and the other to the left front wheel-speed sensor.
Do you have a clear path from pin 7 on the diag socket to the ABS ECU?
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Thanks for that. I'll check the white wires.
Just to be clear, the diag plug seems to have 7 pins. Is pin 7 the bottom right hand one?
I'll check it friday
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The diag plug is the 16-pin one. Maybe the white/black wire?
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