nuc

ABS light comes on after driving several feet at 5-10 mph. Bad sensor or problem in circuit.

If I jack each corner and spin the wheel with a rotary tool with engine running, I should be able to identify which wheel is the problem, by when the ABS light pops on.

Right?

'84 euro 5 spd.

nuc

Yup,

Worked fine. All corners fine when spinning, until I got to lft. front. And up popped the ABS light. Hooked up the trusty DMM to sensor while wheel was spinning, and it showed 0.0V. Time for a new (to me) sensor. Anyone have a front ABS sensor they would like to donate -shipping?

Thanks

'84 euro 5 spd.

Landseer

Those are NLA and hard to find. I suggest checking with the gentleman DougM who is parting out the 84 Euro.

So how did you make this test? Were the rear wheels spinning and registering a speed output on transmission when you spun the front?

I have this problem to deal with also.

What do scale do you set the DVM on in order to get a signal from the sensor ( which is then unplugged )?

nuc

Spun each rear wheel individually, then just to be sure drove them in 2nd while on stands. No light. Spun rt. front, no light. Spun lft. front, and there was light! Hooked up DMM while spinning and no volts. Either sensor is bad or there is a break between it and connection at lft. fender.

Someone must have one of these sitting in their parts bin

lonnie77

You can check the circuit with the sensor disconnected at the connector with an ohm meter. I forgot what the resistants is, 45 or75 ohms. The sensor wires can be soldered together to complete the circuit and the light should go out.

jon928se

From my dim memory of the logic and ignoring the 0.0V reading you actually proved that all but the lft front don't work. Assuming that the 3 wheels you weren't testing were stationary at the time of testing.

If you get an error from one wheel when the others are stationary it proves that the sensor to that wheel is working otherwise the ABS brain would continue to think that the car had not yet moved.

The easiest way to pinpoint failed sensors is to measure the resistance across each sensor (IIRC it's about 800-1000 ohms) starting at the ABS computer harness plug and then working your way nearer to the sensor itself to prove that it's not one of the connectors in the line that is the problem. You should also check the resistance between the sensor wires and ground - it should be infinite.

These sensors normally fail by shorting internally to the case of the sensor while still showing an acceptable resistance between the sensor wires. This will show up as a resistance between one sensor wire and ground = to X where X is between 0 and roughly 1000 ohms. The other wire on the sensor will measure roughly 1000-X ohms - all depnds upon where the short to ground is.

nuc

Great info. Jon.

I looked further into it and after some more testing I found no continuity at the rt. front wheel sensor, even when testing directly at the sensor to take the wires out of the equation.

All the others had ~equal continuity.

I have been in contact with John Speake in the UK and he feels that using a later sensor in place of the earlier should work, except needing to lenghthen the shortened harness.

He said the tech info for MY 86 page 50 has the info. of when the teeth changed for that MY. And it says

"the sensor stays the same but the wiring harness is different".

What do you think?
If we are able to substitute a later sensor, we would not have any NLA problems anymore.

Brett928S2

Hi

I had exactly the same problem as you and did the same tests, with the same result..

BUT... it wasnt the sensor... it was the sensor lead that goes back to the connector in the inner wing, which had rubbed and was earthing...

The only way you will find out if its that is either to change the sensor which MAY be perfectly good...or check continuity between the sensor plug at the sensor and the abs brain end...

All the best Brett

nuc

Hi brett,

I removed the sensor and have no continuity anywhere, even where the wires begin at the sensor. I did test each sensor wire individually and they tested fine. So the "break" must be in the sensor. Trust me, I was hoping for a chafed wire, less money and headache All the other sensors showed ~equal continuity at the pin connectors.