P38 DSE Error msgs EAS,ABS,SRS,TC

1997 P38 DSE. I have recenty been getting EAS,ABS,SRS,TC messages come up on dash and speedo stops working. The fault usually come up whilst driving, if I drive on, they usually disappear in about half a mile.
The alternator has been replaced (after the messages started) as its output was a little low. Now have 14.2/14.4v at the battery when the engine is running.
I have a Nanocom and it displays a reading around 13.5v on the instruments settings of the Nanocom and 14.2v as an input on the gearbox ECU. It looks to me that the gearbox ecu and becam share the same earth so I don't think it is this. I haven't had the fusebox apart, but there is no smell or signs of shorting.
The battery turns over the engine like a good un, but a load test results in a reading of 12.4v I've read that anything below 12.5 can be a problem on a P38. Could it be this despite the alternator presenting 14v?
Anyone had this problem and found the cause?

You previous alternator probably kicked out 13.8V?

I'd swap the battery for a known good one and check the earths are all clean first.

RC51Rider said:

1997 P38 DSE. I have recenty been getting EAS,ABS,SRS,TC messages come up on dash and speedo stops working. The fault usually come up whilst driving, if I drive on, they usually disappear in about half a mile.
The alternator has been replaced (after the messages started) as its output was a little low. Now have 14.2/14.4v at the battery when the engine is running.
I have a Nanocom and it displays a reading around 13.5v on the instruments settings of the Nanocom and 14.2v as an input on the gearbox ECU. It looks to me that the gearbox ecu and becam share the same earth so I don't think it is this. I haven't had the fusebox apart, but there is no smell or signs of shorting.
The battery turns over the engine like a good un, but a load test results in a reading of 12.4v I've read that anything below 12.5 can be a problem on a P38. Could it be this despite the alternator presenting 14v?
Anyone had this problem and found the cause?

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If speedo stops working that is a problem with ABS sensors. Make sure they are all pushed in until they are touching the reluctor rings. Good diag would help. Nanocom or similar.

Fitted a new battery and initially it looked like this had fixed the problem. Then the ABS fault came up on startup with no pressure in the system. (Brakes still working just depressurised). Got the short distance home and parked up overnight. Go to start it this morning and it just spins over. Had the car almost 6 years and it has always been a reliable and instant starter, seems unlikely that its developed another fault at the same time, but I'm at a loss what could be common to the two problems. Its been a great work horse, however it may be time to say goodbye as its not worth spending a great deal on it.

I should add that the ABS ECU does not show any faults, however although the Nanocom is communicating with the ECU is doesn't show anything under settings either, ciuld the ECU be duff? They seem quite cheap on eBay are the petrol and Diesel ones the same?
Not much point sorting the ABS though until I get it running again.

RC51Rider said:

I should add that the ABS ECU does not show any faults, however although the Nanocom is communicating with the ECU is doesn't show anything under settings either, ciuld the ECU be duff? They seem quite cheap on eBay are the petrol and Diesel ones the same?
Not much point sorting the ABS though until I get it running again.

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Try removing and replacing the OBDII plug a few times or cleaning the contacts on the socket. Gems are Wabco C. (Two wheel TC). Motronic are Wabco D (Four wheel TC).. Diesel can be either Wabco C or Wabco D. Before 1999 C after D.

Some earlier ones had no traction control at all, only ABS. Think the ECU was different for them, IIRC.

Grrrrrr said:

Some earlier ones had no traction control at all, only ABS. Think the ECU was different for them, IIRC.

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Think there maybe a clue to TC fitment with the lamp coming on.

No luck on the ODBII plug.
However I have established that the ABS pump is working by removing the pump relay and jumping 30 to 87 on the socket.
85 is also connected to ground. 86 however has no power. I know this is ignition controlled, but can anyone tell me where the connection on 86 go back to, I can't see it in the diagrams RAVE has?
I also took the fusebox out and looked at the surface of the fuse board - no signs of damage or burning but unable to do more than visually check it.

As said before if the speedo stops working it is usually a problem with the ABS speed sensors on the wheels. Check them as advised. All the functions showing faults need a speed signal to work properly. If there is no speed signal they throw a fault. Nothing to do with ABS pump. You need some good diag as said earlier, without it you can bugger about forever and not find the problem.

I understand that ABS speed sensors provide the signal to the speedo. I had this was working prior to the fault I now have, which is the ABS pump not operating when the ignition is on or with the engine running and the braking system is depressurised.
I have a Nanocom, but it just isn't giving any diagnostics from the ABS ECU. I feel the priority is to get the ABS pump working again and see if I still have any faults. The problem at the moment is there is no power on the ABS pump relay - I believe this should be present when the ignition is on regardless of the ABS sensors but I haven't yet determined where the power for connection 86 on the relay comes from. I'm currently suspecting either the fusebox or the ABS ECU is the culprit but I don't want to purchase either based on a stab in the dark, I want to diagnose the problem as far as possible.

To clarify, there is power to the ABS relay on connection 30, but no power to the coil on the relay (connection) 86.

RC51Rider said:

I understand that ABS speed sensors provide the signal to the speedo. I had this was working prior to the fault I now have, which is the ABS pump not operating when the ignition is on or with the engine running and the braking system is depressurised.
I have a Nanocom, but it just isn't giving any diagnostics from the ABS ECU. I feel the priority is to get the ABS pump working again and see if I still have any faults. The problem at the moment is there is no power on the ABS pump relay - I believe this should be present when the ignition is on regardless of the ABS sensors but I haven't yet determined where the power for connection 86 on the relay comes from. I'm currently suspecting either the fusebox or the ABS ECU is the culprit but I don't want to purchase either based on a stab in the dark, I want to diagnose the problem as far as possible.

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Look at relay 2 ABS power relay (yellow) second from left bottom row of engine bay fuse box nearest wing.

Hi wammers,
Same issue on relay 2 - power on 30 but not on 86. Then checked the 5A fuse F24 for ABS. No power on input side of the fuse. Looks like this fuse powers the ABS ECU (or the ALB ECU as RAVE calls it in the electrical trouble shooting manuals) which would explain the non responsive ECU on Nanocom, and probably a lack of communication back to the BECM.
Jumpering power to the output side of the fuse resulting in RL2 audibley latching, although RL17 (ABS pump relay) doesn't trigger, so the ABS pump doesn't run.
Oddly a digital multimeter on 86 of RL2 only shows 12v for an instant and drops down to 0v in not much more than a second - not what I would expect to see. 0v on 86 of RL17.
Leads me to think it is the fuse box after all, what do you think?

The ignition switched power in the fuse box comes from RL15 in the underbonnet fuse box. This gets it's power for both the coil and the relay contact direct from the main +ve feed into the fuse box.

Control for this relay comes from the BECM - and will show ground when the ignition is in any of Pos I,II,III. The wire that controls it is a White wire in pin 8 of C173 (Purple connector into fuse box). It is fed out of the BECM on pin 9 of C120, which is the 14way Yellow connector on the front of the BECM (top row at the front, second from the transmission tunnel.

It would be fairly easy to check this is operating correctly with a multimeter, and will tell you if the fuse box or RL15 are at fault - or whether the ignition feed is not coming out of the BECM properly - which if that is the case, it could be as simple as a blown diode or broken track on the power board of the BECM.

The ABS pump itself is switched on/off by the pressure switch. The pump relay is powered from the ignition feed from RL15 - and then grounding to the ABS pump relay is controlled by the pressure switch attached to the pump housing.

If you aren't getting ignition power to the ABS relay, then I would look at RL15, and check to make sure the ignition feed from the BECM is working as it should.

Hope this helps,
Marty

RC51Rider said:

Hi wammers,
Same issue on relay 2 - power on 30 but not on 86. Then checked the 5A fuse F24 for ABS. No power on input side of the fuse. Looks like this fuse powers the ABS ECU (or the ALB ECU as RAVE calls it in the electrical trouble shooting manuals) which would explain the non responsive ECU on Nanocom, and probably a lack of communication back to the BECM.
Jumpering power to the output side of the fuse resulting in RL2 audibley latching, although RL17 (ABS pump relay) doesn't trigger, so the ABS pump doesn't run.
Oddly a digital multimeter on 86 of RL2 only shows 12v for an instant and drops down to 0v in not much more than a second - not what I would expect to see. 0v on 86 of RL17.
Leads me to think it is the fuse box after all, what do you think?

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Don't know to be honest, not an absolute leccy wizard. Marty would be better. But if you look at ABS system descriptions it does say if a fault occurs were the system needs to be shut down then power to pull relay 2 is cut. Now whether that is the ECU failed or the ECU being isolated by relay 2 i don't know.

RL2 is the main power feed for the ABS ECU. This is actually controlled by the ABS ECU itself, and the grounding for it goes to E167
The feed for RL2 is from F27, and dedicated to the ABS system.

If everything else ABS wise appears to be working other than the pump, then I would suspect either fuse box, somewhere around the ABS relay area... or the pressure switch. You could disconnect the pressure switch and bridge the connection on the pins that control the ABS pump relay. If the pump then runs (don't leave it running otherwise it won't switch off - just power it on long enough to see if it runs as it should!!!!) then the pressure switch is faulty and it's not allowing the pump to run as it should. If the pump still doesn't fire up, then it comes more back to fuse box again.

This looks like a classic case of a failing under bonnet fuse box.

If you replace with a good used fuse box, to match them correctly make sure that the pins underneath are exactly matched like for like.

Thanks guys, I confirmed that the ignition is coming from the BECM as it should. Will take a chance with a second hand fuse box, although I notice most breakers on flebay don't seem to be aware the fuse box change fo MY99 and MY00 - or is there a chance that earlier (pre 99) DSE's don't mind which diesel fuse box is fitted?
Will report back if this is successful, but it may be a few weeks, its not my daily runner.

RC51Rider said:

Thanks guys, I confirmed that the ignition is coming from the BECM as it should. Will take a chance with a second hand fuse box, although I notice most breakers on flebay don't seem to be aware the fuse box change fo MY99 and MY00 - or is there a chance that earlier (pre 99) DSE's don't mind which diesel fuse box is fitted?
Will report back if this is successful, but it may be a few weeks, its not my daily runner.

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You need to fit the correct fuse box. What is your VIN number?