ABS not working

[chargerbandit]

Hey guys, got a 93 Calibra 8v and my ABS does not work, when I turn the key the ABS light does not come on and doesn't work when braking. The ABS rings are a bit worn but I'm guessing its the computer because it doesn't diagnose. I heard that from 92 on the Calibra ABS computer and hydraulic module are both in one? Any tips on what I should check or should I just replace the whole module?

[Cliff]

I think that ABS ECU is separate and under the plastic housing next to the passenger seat (assuming UK model). Or if it is the 2EH then it is on the block. According to Haynes depending on the shape of the unit it's serviceable or not. Flat cover is not serviceable.



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[Cliff]

You can check fuse and surge arrester relay. also if you jumper pins A and K if you have a wire at K for diagnostics. If you're getting no light maybe you have a bad bulb or feed. viewtopic.php?f=18&t=22108


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[chargerbandit]

It seems like my ABS is the first type so I guess the issue is in the ABS ECU.

Took a look at the passenger footwell, got a random relay hanging off and I have no idea what any of this does, the big Bosch box is the engine ECU or ABS? My car is a 1993 German made Opel Calibra 2.0 8v. Where do I find these surge arrester relays? The diagnostic definately shows nothing.

[Cliff]

Hi! So you have the 2E version which is good because it's serviceable. Your picture with the larger metal box is the main ECU so not ABS.

So, the surge arrest relay is located in the engine bay fuse box, look at this guide - it's relay 2 in the picture attached.

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First thing is to check that the relay tests OK and you have power at the relay socket (you'll need Haynes wiring diagram for the pinouts if you're unsure how to read markings on the relay). If so then the next steps would be to check the relays in the 2E unit itself - you'll need to remove the cover by undoing the screw.

If you're not sure how to test the relays then ask and I'll try to describe it - you'll need a basic multimeter or test lamp.


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[chargerbandit]

Thanks Is the engine fuse box behind the ABS in the engine bay? Because in my case there is no engine fuse box then.

Edit: Engine pic

I did notice I'm missing a foglight relay haha.

[Cliff]

Hi again - sorry for the delay. Confusing you don't have the engine bay box but that's just because I haven't seen that before.

Here's the wiring diagram for early models:



And late models:



Early models show the existence of the surge arrester relay which should be in the engine bay. Later models didn't have it. Both are protected by fuse - I assume you've checked that's ok?

Early model ABS control units were separate and mounted at the side of the drivers side seat (assuming this is an Opel?? Otherwise passenger side seat). Between the seat and the door is what I can only describe as a plastic "lump" hiding the carpet that you can see on the opposite side. Not the same as the footwell covers that you removed in pics above. You remove the cover lid and the ECU is there. Later models were attached to the hydraulic unit. I think yours is later 2EH not 2E as I said earlier but checking for the ECU in that plastic lump would confirm.

If you confirm that fuse is OK, that this is later model and no ECU at side of seat (here's a pic):



Then it's time to check for power at the ECU hydraulic unit in the engine bay.

So:

1. Check fuse is ok (swap with another to be 100% unless you have a tester)
2. Check if this is early or late by confirming where the ABS ECU is - is it next to the seat or not
3. Check for power at the hydraulic unit




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[chargerbandit]

Okay thanks for the tips. So I searched for the ECU in the interior, it is not there. Then I tried multiple fuses and probed the socket and the power is there. Then I unplugged this big connector at the ABS unit (which looks like the one at the interior ECU, so I guess my ECU is under the ABS?) and the plug itself doesnt have power, but the pins on the ABS socket have power, ranging from 4.7 volts on some, I think one pin has around 11v and one was 3v. Picture attached, what's the next step, new ECU?

[Cliff]

Yes your ECU is on the block. You can do one more thing which is leave the ABS ECU plug unplugged, remove the lid from the ABS unit and remove then test the two relays. In the meantime I'll see if I can find a pinout for the connector so you can check you have 12v on the right pins.


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[Cliff]

Note: there are two types of unit, one has the relays plugged in, the other has them soldered in. So only try to remove them gently - if they're soldered there's nothing more you can do with that.


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[chargerbandit]

So I took the cover off today, took out the relays and tested them, I am pretty sure they work fine. So I was trying some other points and these leads that come from the side give almost no reading on my multimeter (something like 0.2V) even when the car is running. Maybe that is the source of my problem?

[Cliff]

Ah-ha - yes - is it a 4 pin connector?


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[chargerbandit]

This is the connector, I went back and remeasured the stuff, the top two pins show 12V while the bottom two nothing. So I went and started remeasuring those other wires and when I grounded I think the yellow wire the ABS started making noise? Also those wires previously showed nothing now they mostly show 12V and it confuses me. I am out of ideas here.

[Cliff]

Check the connections as follows:

Pin 1 to earth - 12v with ignition on
Pin 2 to earth - permanent 12v
Pin 3 to earth - 0 ohms resistance (this should be earth/ground)

[Cliff]

If pin 3 has a high resistance to earth/ground then you have a bad connection somewhere - you can trace it back and find the break or simply splice to ground (new wire).