OBD doesn't appear to be working

[kiloran]

The ABS light is on permanently in my car and the ABS system isn't working either. Tested recently by a deer

Been like it for months and so I'm trying to get it fixed way in advance of the next MOT (which isn't until Jan 21).

I've followed the guidance for using the OBD connector ('92 940 SE 2l Petrol - 2 boxes bolted to the passenger strut tower) but I don't appear to be getting any codes from any of the connections (not even 1-1-1 to indicate no fault). I've cleaned the bullet connector and the sockets as best I can.

Procedure I used was:

• Turn ignition key to position 2 (so all the dash lights are on)
• Plug bullet connector into socket 3. The diag LED lights, but dimly (this is without pressing the diag button)
• Press the diag button, LED lights brightly. No code readout.
• For all the other positions on the connectors the LED doesn't light dimly, and I don't get any codes either.
• Occupied positions are 2,3, and 6 on connector A and 5 on connector B

Does this point to the OBD system itself being at fault?

[Laird Scooby]

Originally Posted by kiloran

The ABS light is on permanently in my car and the ABS system isn't working either. Tested recently by a deer

Been like it for months and so I'm trying to get it fixed way in advance of the next MOT (which isn't until Jan 21).

I've followed the guidance for using the OBD connector ('92 940 SE 2l Petrol - 2 boxes bolted to the passenger strut tower) but I don't appear to be getting any codes from any of the connections (not even 1-1-1 to indicate no fault). I've cleaned the bullet connector and the sockets as best I can.

Procedure I used was:

• Turn ignition key to position 2 (so all the dash lights are on)
• Plug bullet connector into socket 3. The diag LED lights, but dimly (this is without pressing the diag button)
• Press the diag button, LED lights brightly. No code readout.
• For all the other positions on the connectors the LED doesn't light dimly, and I don't get any codes either.
• Occupied positions are 2,3, and 6 on connector A and 5 on connector B

Does this point to the OBD system itself being at fault?

Not necessarily. Your car is on a changeover from Bosch ABS to Bosch ABS-2E. The latter has self-diagnostics (readable with the underbonnet reader) and the former doesn't. I wouldn't be at all surprised to learn you still have the ABS rather than ABS-2E system despite the fact you have the fault code reader under the bonnet.

When you first turn the key to position 2 (without starting it), does the ABS light come on and also does the battery charge warning light?
When you start the car, does the charge light and ABS light go out? If so, how soon after does the ABS light come on?

[Ian21401]

I thought that cars of our vintage only had one OBD box fitted.
My 1992 940, B200F engine, only has one OBD box mounted on the nearside turret. The car is fitted with Bosch LH2.4 Jetronic fuel injection.
The box has six sockets but only two are operational. Socket 2 for fuel system checks and socket 6 for ignition system checks.
There is no ability to check for ABS faults.

[kiloran]

ABS light comes on with key in position 2, as does the battery light. Battery light goes out on start, ABS light stays on. In addition to the deer test I've also done a proper brake test with a both feet out emergency stop on a wet road. It's amazing how cadence braking muscle memory comes back when it's needed! Definitely no ABS available and a delightful stench of Taiwanese Ditch Finder in the car

How do I tell which Bosch system I have? Here's a pic.

My car is slightly difficult to pin down spec-wise. Manufactured '92, first registered Jan '93, and was actually sold by Volvo Diplomatic Sales to an officer on an RAF base in Germany (RHD though). Steel wheels, heated seats, electric windows, manual sunroof, non-metallic paintwork, and badged as an SE.

[kiloran]

Originally Posted by Ian21401

I thought that cars of our vintage only had one OBD box fitted.
My 1992 940, B200F engine, only has one OBD box mounted on the nearside turret. The car is fitted with Bosch LH2.4 Jetronic fuel injection.
The box has six sockets but only two are operational. Socket 2 for fuel system checks and socket 6 for ignition system checks.

Definitely 2 boxes on mine, with four sockets wired up

[Laird Scooby]

Originally Posted by kiloran

ABS light comes on with key in position 2, as does the battery light. Battery light goes out on start, ABS light stays on. In addition to the deer test I've also done a proper brake test with a both feet out emergency stop on a wet road. It's amazing how cadence braking muscle memory comes back when it's needed! Definitely no ABS available and a delightful stench of Taiwanese Ditch Finder in the car

How do I tell which Bosch system I have? Here's a pic.

My car is slightly difficult to pin down spec-wise. Manufactured '92, first registered Jan '93, and was actually sold by Volvo Diplomatic Sales to an officer on an RAF base in Germany (RHD though). Steel wheels, heated seats, electric windows, manual sunroof, non-metallic paintwork, and badged as an SE.

Nice pic but it's from the wrong place. Inside the cabin, remove the trim under the drivers side dash above the pedals. Above the pedals you'll see an ECU - get the part number off it if you can, you may need to unclip the cradle (it's at the easiest end to get to thankfully!) and loosen the ECU to get the part number which will be a 10-digit Bosch part number.

If you happen to see a relay clipped onto the cradle, have a feel (or use a mirror and torch) to see if there's a fuse on the top of the relay, a red 10A fuse. Remove and inspect this fuse if so and any doublt, renew it.

If it has this relay, it's the ABS, if it doesn't it's the ABS-2E system. Chances are if it has the relay, the ECU will be 0 265 101 028.

As for your paintwork, if i'm not mistaken that should be colour code 603 - Dark Bule (Metallic) - worth checking!

[kiloran]

Is this the relay? Looks like the part number is 1 358 568 (Made in Germany) - can't quite make it out because I can't get the camera far enough away to focus

It's also stamped 897169 10A (and has a red 10A fuse in the top). Just above the throttle pedal with a multiplug on the bottom

[kiloran]

Well, that's fixed, thanks everyone.

Pulled the 10A fuse on top of the relay, couldn't see anything wrong with it. Didn't have a spare to hand so popped a 15A in there temporarily (I know, I know...)

OBD now works. 1-1-1 reported for all occupied diagnostic positions. Initially position 3 for the ABS wasn't working but a bit of wiggling and contact cleaner sorted that out.

Cleared the codes, ABS light now off and staying off. Haven't been able to test whether the system is actually working (too busy, will go out later) but I've taken it for a 15 minute test drive up to 60mph and all is fine.

Relay now has the original 10A fuse back in it and ABS light is off (after initial startup)

Now on to the next MOT snag - weak washer performance on the passenger side. And then reversing lights.

[Laird Scooby]

Originally Posted by kiloran

Well, that's fixed, thanks everyone.

Pulled the 10A fuse on top of the relay, couldn't see anything wrong with it. Didn't have a spare to hand so popped a 15A in there temporarily (I know, I know...)

OBD now works. 1-1-1 reported for all occupied diagnostic positions. Initially position 3 for the ABS wasn't working but a bit of wiggling and contact cleaner sorted that out.

Cleared the codes, ABS light now off and staying off. Haven't been able to test whether the system is actually working (too busy, will go out later) but I've taken it for a 15 minute test drive up to 60mph and all is fine.

Relay now has the original 10A fuse back in it and ABS light is off (after initial startup)

Now on to the next MOT snag - weak washer performance on the passenger side. And then reversing lights.

Yes, that's the relay and as you've found, the contacts in the fuseholder got dirty which caused the fault. Glad it's sorted and you know where to look if the ABS light stays on with the ignition again. There are other things that can cause it but that's the first port of call.

Weak washer performance - renew the T-valve on the bonnet. They have a habit of failing and when they do, they leak, all over your dizzy cap resulting in a breakdown!

https://www.ebay.co.uk/itm/Volvo-C30...e/283452421138

I can't find the 7/940 T-valve on fleabay, that one is almost identical (the leg is shaped differently on the 7/9xx) but will do the same job.

While it's disconnected, either use dome compressed air to back flush the jets or replace them with S/V40 jets with the fan/mist spray. They're cheap and you'll be glad you did!

https://www.ebay.co.uk/itm/2X-Volvo-...y/383174799682

Pull the rubber hose off the jets from underneath and use an 11mm deep socket or box spanner to go over the jet from underneath so the flats on the inside of the socket line up with the fingers on the jet, push towards the bonnet and you'll feel the fingers compress then the jet pops out. I normally clean and polish the little section of paintwork that's revealed before fitting the new jet, it's easiest if you feed the hose through, connect the jet (complete with rubber gasket under it and then just push the new jet into position.

Could be worth having the washer bottle out completely and cleaning it inside and out then flushing the whoel system through a section at a time with clean water to get rid of any gunge in the pipework. I can give you more info on that if you like.

[Wagon Sailor]

Just for future reference, some Honda wheel/speed sensors integral to the abs system can sometimes stop working if they get very dirty. I don't know about 940s. Worth checking from time to time?