Wiring Diagram for ABS on 1994 Thema

[Angle Grinder]

Hoping someone might have a workshop manual for the Series 3 (1992 - 94) Thema range as I'm struggling to find the reason why my ABS light is coming on.

Here’s the story:
•   The light first came on in December just at the time we had that very cold blast. Maybe related?
•   The light comes on as soon as the ignition is energised and stays on. The car doesn’t need to be driven for the fault to be detected.
•   I tested the ohms across each sensor and they all sit around 1100 ohms.
•   I’ve checked the protective fuse (or what I reckon is the right fuse) and swapped around relays.
•   I removed the connector and squirted with WD40 and did the same with the 2 relays (Bosch 0 332 002 171) at the ECU.
•   Also been round all the hubs and done my best to clean the faces of the ABS sensors and the phonic rings.
•   When the car has had a good run of an hour and is restarted with a still warm engine, the ABS light often behaves as it should and goes out after a few seconds. It doesn't flicker or change state during a drive, and either goes out right away or stays on constant.

[SanRemo78]

Hi, not sure if it's any help but I have an Alfa Romeo manual for the 164 - similar age with a Bosch ABS system - that I could scan and email the relevant pages to you? There's only 8 pages but there's no trouble shooting guides or wiring diagrams unfortunately..... I may have a wiring diagram somewhere, if you need that let me know and I'll have a rummage!

It's odd that you have an intermittent issue. From my attempt to install ABS on the Stratos replica I learnt that the system on the 164 has a warning light on the dash that illuminates when the ignition is switched on. It then does a check of the sensors and pump solenoids (I think) and if all are present it switches off the light. At speeds over 5kmph the system reads the wheel signals and if it detects variations from any sensor it goes into failsafe and illuminates the warning light.

If you have a light that stays illuminated I would expect that it's seeing a wiring issue at one or more corner? Don't be tempted to check for continuity with 12v, I think that will damage the wheel sensors. If there is no evidence of chafed/damaged wiring (check the semi rigid cables where they enter the sensor body as that's an area I've seen breakages). I'd also be looking at the gaps on each sensor to the trigger rings and the state of the reading surface of each sensor in case they're damaged. The gap ought to be between 0.4 and 0.6mm but it should work with a range between 0.25 and .75mm according to handwritten notes on the manual I have. I think it might be wise to check the gap around 360 degrees of wheel rotation in case you have a damaged trigger ring running eccentrically or out of true? This may be caused by worn wheel bearings? If one is out of tolerance it might explain why it's okay at one start up but not at the next however I would expect a fault such as that to generate a fault as soon as the car is moving over 5KmPH.

Drop me a PM with your email address if I you need me to send anything over.

Guy