Antiskid + Brake failure stop safely - Error expert needed!

[danc]

Being temperature related seems quite likely - it's only ever happened in two scenarios:

22+ degrees outside, 20+ min driving time... then

1) Sudden traffic queue, stop, brakes on and off as traffic rolls forward, limp mode from lifting foot off brake (10 times so far, once with DEM fuse out)

2) Fast overtake, kick-down accelerator, possible braking afterwards, limp mode shortly afterwards (this scenario only happened once)

Do either of the ECM, TCM or BCM have fan-based cooling systems which are susceptible to failure?

[danc]

In another recent post, I mentioned the sound of clicking relays on braking coming from the car boot. On investigation, I tracked it down to a 7-way Towing Electrics kit.

The noise was only more noticeable recently because I'd removed some of the boot liner to access the battery and REM fuse box.

It's a long shot but could the towing kit be the source of my problem?

The cables are soldered directly into the lighting cables for brakes, indicators and lights. Plus, one of the errors logged was "BCM 0150 Stop (brake) lamp switch Signal outside its permitted range".

For now, I've removed the power fuse to the unit just in case.

I've found only one other reference on Google and, of course, may be able rule it out tonight if limp mode kicks in again.

[SonyVaio]

Yes, any add on wiring bits can cause major issues if not fitted correctly.

If you have any add on stuff it would be worth isolating to check.

[bandit1200s]

Nearly 9 months I have had problems related to this. BBA Reman tested my old BCM and diagnosed it as faulty and then proceeded to send me an uncompatabile replacement. I have just fitted a compatable BCM today from EVOLV Parts that I was assured that it would plug and play and the ABS would go out. WELL IT NEVER. I have had my DIM and CEM tested by VolvoDiagnostics and they passed. Tomorrow I am going to buy a volt meter and join in. I expect this will sort it as my OBD11 connector I got with a Torque app wont talk to the volvo but it will talk to my old citroen C15 van.

Cant wait

[KBB]

Have you had the ABS codes read. If you have a cheap reader it will unlikely be able to communicate with BCM but should comm with ECM.

If it will not connect with ECM then you may have a network issue. If you can get the BCM codes read with a decent reader.

[bandit1200s]

Originally Posted by KBB

Have you had the ABS codes read. If you have a cheap reader it will unlikely be able to communicate with BCM but should comm with ECM.

If it will not connect with ECM then you may have a network issue. If you can get the BCM codes read with a decent reader.

I had a test done at Volvo last year and nearly every fault code came up. I have had the whole wiring loom from under the bonnet out and dried. THE ECM cleaned and all the other bits as previously mentioned. Problem is that it has now passed its MOT date so I cant even drive it to Volvo to have another test done. I even bought a VIDA DIce from China but that would not install on my laptop correctly so that had to go back.

My gilfriend bought it off a friend because she liked it, say no more

[bandit1200s]

Just bought a new test meter and these are my results

Resistance between CAN high and CAN low
Pins 6 : 14 = 118.6

CAN high
Pins 6 : 4 = 2.5v
Pins 6 : 5 = 2.5v

CAN low
Pins 14 : 4 = 2.36v
Pins 14 : 5 = 2.36v

I do hope that you can help me out with this

[KBB]

Originally Posted by bandit1200s

Just bought a new test meter and these are my results

Resistance between CAN high and CAN low
Pins 6 : 14 = 118.6

CAN high
Pins 6 : 4 = 2.5v
Pins 6 : 5 = 2.5v

CAN low
Pins 14 : 4 = 2.36v
Pins 14 : 5 = 2.36v

I do hope that you can help me out with this

Your resistance values between DLC pin 6 & 14 are a text book open circuit on one leg of the network. Can you confirm that this test was conducted with the battery disconnected?

[bandit1200s]

The battery had had the black lead crossed over to the red side to discharge the whole system overnight before I tested it. The results are with the battery disconnected.

Just so you know, I have got a replacement BCM module on the vehicle. It is the same serial number as the original but not the original as a repair company lost my original.

[KBB]

Give me some time and I will put together a proposed test plan this will involve disconnecting every ECU on the high speed network so give yourself a couple of hours test time.

Can you confirm vehicle, fuel type and year. Engine code would be helpful. What are you like with a test meter and working with wiring diagrams?