chrisa3

iTrader: (1)

I have been searching the forums for solutions to ABS light probs. I have found a few similar probs but non of the threads have had solutions posted.

Basically, my 2wd saff's abs light is staying on constantly. comes on when ignition is turned on, doesnt go out, just stays on. now so far i have checked the following and im at a loss. Anyone had similar problems and found a solution???

- tested all abs sensors. all reading around 1000 ohms.
- Tested the fluid level sensor and its fine.
- Tested the two pin ABS plug on level sensor is fine, getting continuity on both pins and bridging the pins doesnt make the light go out.

Tried a different ABS ecu
was told cars upto 1989 had a orange relay in relay VII. mines missing, but the fusebox is not wired for this relay (mines registered 28/11/1988).

Im now at a loss. It failed its mot on the abs light, and I need to get it fixed and restested before Wedesday next week.

Any advice would be greatly appreciated

tabetha

I assume the pumps pressurising, ie you're getting a good pedal ?
Check your abs rings for damage.
tabetha

RS500/364

Afew times it has been the cap on the fluid makes the light stay on

opposite lock

iTrader: (3)

sorry to hear this. You may be better off posting in the 3door/saff/rs500 room too?
i cant help you out i,m afraid but someone here will post up, i think msd have good knowledge of this system too

jon@work

iTrader: (5)

ignition on
do you hear the ABS pump working ?

if you do :
ignition off
unplug ABS ECU connector
remove connector cover
have you got continuity between terminals 9 and 10 ?

chrisa3

iTrader: (1)

Yep, pump turns on with ignition, primes and switches off once upto pressure. All 4 brakes bled up ok. Passes all the MOT braking tests without issue.

Whats confusing me is the relays / wiring. I was told that upto may 1989 (the haynes manual states this too), there should be an orange relay in socket VII under the bonnet. My fuse box isnt wired for this. The I read a few posts on here that only the 4x4 had the orange fuse in VII.

I have checked under the passenger dash and there is only the two relays there as per 2wd wiring (1 purple and 1 green).

chrisa3

iTrader: (1)

ABS pump is the one with reservior attached?? yes that whirrs / primes and stops when upto pressure.

i have removed the reservoir cap and the red light eluminates on the dash with the handbrake disengaged, so the level sensor is fine. I have bridged the two pins (two pin connecter) and the light stays on, confirming level sensor ok. I have tested pins 9 & 10 and do have continuity, so wiring between ecu and level senor is ok too.

jon@work

iTrader: (5)

have you got wires in terminals 12 and 19 of the ECU connector ?

chrisa3

iTrader: (1)

12 isnt present but 19 is there (black and green)

jon@work

iTrader: (5)

what colour is the wire to terminal 2 ?

chrisa3

iTrader: (1)

black

jon@work

iTrader: (5)

1. what is the resistance between terminals 11 and 18 (ECU unplugged, ignition off) ?
2. what is the resistance between terminals 11 and 1 (ECU unplugged, ignition off) ?
3. what is the resistance between terminals 11 and 15 (ECU unplugged, ignition off) ?
4. what is the resistance between terminals 11 and 16 (ECU unplugged, ignition off) ?
5. what is the resistance between terminals 11 and 17 (ECU unplugged, ignition off) ?
6. what is the resistance between terminals 11 and 18 (ECU unplugged, ignition off) ?
7. what is the resistance between terminals 11 and 33 (ECU unplugged, ignition off) ?
8. what is the resistance between terminals 11 and 34 (ECU unplugged, ignition off) ?
9. what is the resistance between terminal 9 and earth (ECU unplugged, ignition off) ?
10. what is the resistance between terminal 10 and earth (ECU unplugged, ignition off) ?
11. what is the resistance between terminals 1 and 3 (ECU unplugged, ignition off) ?
12. what is the resistance between terminals 1 and 20 (ECU unplugged, ignition off) ?
13. what is the resistance between terminals 1 and 8 (ECU unplugged, ignition off) ?
14. what is the voltage between terminals 1 and 2 (ECU unplugged, ignition on) ?
15. with ECU unplugged and ignition off, temporarily join terminals 2 and 8 with a jumper wire. With ignition on, what is the voltage between terminals 1 and 3, and 1 and 20 ?

chrisa3

iTrader: (1)

Hi mate, sorry if i have done this wrong but im no autoelectrician

I have set the multimeter ohms at 2000 and the readings are as follows:

1. what is the resistance between terminals 11 and 18 (ECU unplugged, ignition off) ? 006
2. what is the resistance between terminals 11 and 1 (ECU unplugged, ignition off) ? 0
3. what is the resistance between terminals 11 and 15 (ECU unplugged, ignition off) ? 006
4. what is the resistance between terminals 11 and 16 (ECU unplugged, ignition off) ? 003
5. what is the resistance between terminals 11 and 17 (ECU unplugged, ignition off) ? 006
6. what is the resistance between terminals 11 and 18 (ECU unplugged, ignition off) ? 002
7. what is the resistance between terminals 11 and 33 (ECU unplugged, ignition off) ? 003
8. what is the resistance between terminals 11 and 34 (ECU unplugged, ignition off) ? 1
9. what is the resistance between terminal 9 and earth (ECU unplugged, ignition off) ? 1
10. what is the resistance between terminal 10 and earth (ECU unplugged, ignition off) ? 1
11. what is the resistance between terminals 1 and 3 (ECU unplugged, ignition off) ? 001
12. what is the resistance between terminals 1 and 20 (ECU unplugged, ignition off) ? 001
13. what is the resistance between terminals 1 and 8 (ECU unplugged, ignition off) ? 069
14. what is the voltage between terminals 1 and 2 (ECU unplugged, ignition on) ? 11.63v
15. with ECU unplugged and ignition off, temporarily join terminals 2 and 8 with a jumper wire. With ignition on, what is the voltage between terminals 1 and 3 = 12.19v and 1 and 20 = 12.19v

thanks for this

jon@work

iTrader: (5)

I presume from the results of tests 9 and 10 that the "1" reading on your meter means that there is infinite resistance, or "open circuit". This is OK for tests 9 and 10, but not right for test 8. Test 8 should give a similar resistance result to tests 3 to 7.

Re-do test 8 please, to double check the result.

If the result is the same, there seems to be a problem with either :
1. a damaged wire - namely the blue/red wire from ECU terminal 34
2.the valve block (which is on the passenger side inner wing)
3. corrosion in the valve block connector
4. a dislodged terminal in the valve block connector

Remove the 7-way connector from the valve block, and pull back the rubber boot. Have a look at the terminals and check they look OK. Pay particular attention to the blue/red wire to terminal 6. You may find numbers on the connector. If there aren't any numbers, the brown wire is terminal 1, so terminal 6 (the blue/red wire from ECU terminal 34) is the second from the end furthest from the brown wire (but watch it - there should be 2 blue/red wires at the valve block).

You can check the wire by unplugging the connector from the valve block, and checking for continuity between ECU terminal 34 and the valve block connector terminal 6. Obviously, there should be continuity, or very low resistance. If this is not the case, the wire is damaged and needs to be repaired or replaced.

To check the valve block itself, unplug the connector from the valve block, and check the resistance between valve block terminal 1 (corresponding with the brown wire in the valve block connector) and valve block terminal 6 (corresponding with the blue/red wire from ECU terminal 34). The correct result is a resistance of 3 to 7 ohms.

jon@work

iTrader: (5)

If you have a look at the tests above, tests 1 and 6 are duplicated. Typo from me. You need to do a further test :

what is the resistance between terminals 11 and 35 (ECU unplugged, ignition off) ?

chrisa3

iTrader: (1)

Re-do test 8 please, to double check the result. Same = 1

If the result is the same, there seems to be a problem with either :
1. a damaged wire - namely the blue/red wire from ECU terminal 34
2.the valve block (which is on the passenger side inner wing)
3. corrosion in the valve block connector
4. a dislodged terminal in the valve block connector

Remove the 7-way connector from the valve block, and pull back the rubber boot. Have a look at the terminals and check they look OK (seem ok). Pay particular attention to the blue/red wire to terminal 6. You may find numbers on the connector. If there aren't any numbers, the brown wire is terminal 1, so terminal 6 (the blue/red wire from ECU terminal 34) is the second from the end furthest from the brown wire (but watch it - there should be 2 blue/red wires at the valve block).

You can check the wire by unplugging the connector from the valve block, and checking for continuity between ECU terminal 34 and the valve block connector terminal 6. Obviously, there should be continuity, or very low resistance. No continuity between 34 and 6! If this is not the case, the wire is damaged and needs to be repaired or replaced.

To check the valve block itself, unplug the connector from the valve block, and check the resistance between valve block terminal 1 (corresponding with the brown wire in the valve block connector) and valve block terminal 6 (corresponding with the blue/red wire from ECU terminal 34). The correct result is a resistance of 3 to 7 ohms. Reads 003 ohms

If you have a look at the tests above, tests 1 and 6 are duplicated. Typo from me. You need to do a further test :

what is the resistance between terminals 11 and 35 (ECU unplugged, ignition off) ? = 006 ohms


Does this mean that I have a broken wire betwwen terminals 34 and 6 (the blue and red cable). What does this cable do and do I just cut at both ends and run a new cable between them??

Thanks for all the help matey.. .brilliant

jon@work

iTrader: (5)

yeah - certainly seems like the wire is broken if you've got no continuity

chrisa3

iTrader: (1)

update, i have ran a new wire from pin 34 to pin 6 and have now got continuity between the two pins.

Turned on the ignition but abs light is still on and not going out
any ideas??

jon@work

iTrader: (5)

last thing for today : ABS Sensor Cable Shielding Check

RH rear sensor : Connect ohmmeter between terminals 4 and 1 of ECU.
LH rear sensor : Connect ohmmeter between terminals 6 and 1 of ECU.
RH front sensor : Connect ohmmeter between terminals 7 and 1 of ECU.
LH front sensor : Connect ohmmeter between terminals 5 and 1 of ECU.

Result should be : Infinity

chrisa3

iTrader: (1)

Just checked the above and with the multimeter set to 2000 ohms im getting a reading of 1 on all four of the above. Plug disconnected and ignition off. 1 is the reading it gives for an open circuit and 0 for a fully closed circuit.

I have also checked the abs sensors resistance from the ecu plug and getting 1009 on both rears and around 1040 on both fronts. Starting to do my head in now

chris

jon@work

iTrader: (5)

Seeing as there was a problem with one of the wires feeding the valve block, it could be the case that more than one of the wires was damaged, and now you've disturbed the wiring, a new fault has appeared. May be worth repeating the checks for the valve block wiring, which are :

3. what is the resistance between terminals 11 and 15 (ECU unplugged, ignition off) ?
4. what is the resistance between terminals 11 and 16 (ECU unplugged, ignition off) ?
5. what is the resistance between terminals 11 and 17 (ECU unplugged, ignition off) ?
6. what is the resistance between terminals 11 and 33 (ECU unplugged, ignition off) ?
7. what is the resistance between terminals 11 and 34 (ECU unplugged, ignition off) ?
8. what is the resistance between terminals 11 and 35 (ECU unplugged, ignition off) ?

chrisa3

iTrader: (1)

Just checked, results above

jon@work

iTrader: (5)

with ignition on and ECU unplugged, have you got continuity between ECU terminal 27 and earth ?

jon@work

iTrader: (5)

if you unplug the ABS ECU relay (the green one), have you got continuity between terminal 85 and earth ?

chrisa3

iTrader: (1)

When you say earth, which earth?? the earth on pin 11 or body earth.

chrisa3

iTrader: (1)

Sorry again, just want to confirm, continuity is when the meter is set to beep for closed circuit??

chrisa3

iTrader: (1)

getting around 1000ohms with ignition on and 017ohms off on ecu pin 27 and body earth.


Getting continuity (beep / 0hms) between pin 85 on the relay plug and body earth point (ignition off)

Chris

jon@work

iTrader: (5)

has the ABS ever worked since you've owned the car ?

is it a 2wd ABS ECU fitted ?

chrisa3

iTrader: (1)

I bought the car as a rolling shell, so its the first time I have had it running. Passed all the MOT brake tests with no problem.

as far as I am aware its a 2wd Ecu, Its the second ecu I have tried in the car and the other one is definately a 2wd one.

jon@work

iTrader: (5)

Unplug ONE end (either end - doesn't matter) of the diode near to the ABS fuses/relays (grey rubber cylinder 2 inches long, brown/red wire one end, blue/green wire the other).

With ECU unplugged and ignition off, temporarily join ECU connector terminals 2 and 8 with a jumper wire. With the ignition on, what is the voltage between terminals 1 and 3 ?

chrisa3

iTrader: (1)

Just checked and its 12v or 12.02 approx

jon@work

iTrader: (5)

when you tested the ABS sensors, did you take the resistance readings at the ECU connector ?

chrisa3

iTrader: (1)

Yes, tested at the ecu connector and at the sensors themselves. Got the same readings at both. Are we both stumped now

jon@work

iTrader: (5)

Plug everything in, except one end of the diode.
Start the engine. Leave it running for a couple of minutes.
What happens to the light ?
With the engine still running, have you got 12V at the green ECU relay terminal 30 (without unplugging the relay, so just pull it out of its socket slightly until you can get your multimeter lead in there, or a short piece of wire) ?

chrisa3

iTrader: (1)

Just tried but battery is flat now. Gonna get a booster pack and get it started later today. Will update later. Thanks for taking the time to help, much appreciated

barry bigfin

Chris have you ever thought that you might have bought a ringer?

chrisa3

iTrader: (1)

No, are you trying to tell me something

On the plus side ITS FIXED

Used some jump leads to get the car running and ABS light is fixed woooohoooo. Must have been the dodgy wire I replaced. Jon you are one clever bloke Would never have found it without your help.. Much appreciated.

jon@work

iTrader: (5)

did you try the last test, or is the diode (and everything else for that matter) plugged in properly ?

chrisa3

iTrader: (1)

Just plugged everything back together as it was before. Only thing that is now different is the wire we replaced.

Genesis

Anyone got any ideas why my ABS lights in the dashboard wont come on. The pumps works fine but no lights - therefore an MOT failure - need help - anyone?