dashboard warning lights staying on.

GrumpyGel · Feb 8, 2017

I can't see how an ABS fault could throw the SRS or MIL lights?

My thoughts are that if its not the dash its the wiring to it.

Thinking about it though, I can't see how a network fault could spuriously generate codes in the ABS ECU saying that the wheels sensors are down.

I wonder if the alternator has developed a fault and is throwing bad voltages around the electronics? Might make the ABS ECU think the sensors are faulty and the SRS detect problems etc.

Skinny Mike · Feb 8, 2017

GrumpyGel said:
I can't see how an ABS fault could throw the SRS or MIL lights?

My thoughts are that if its not the dash its the wiring to it.

Thinking about it though, I can't see how a network fault could spuriously generate codes in the ABS ECU saying that the wheels sensors are down.

I wonder if the alternator has developed a fault and is throwing bad voltages around the electronics? Might make the ABS ECU think the sensors are faulty and the SRS detect problems etc.

Due to the way the canbus on the TD4 works, most of the coms goes through the ABS ECU. The Bosch abs unit has been known to suffer from dry joints and throwing spurious faults.
Mikr

GrumpyGel · Feb 8, 2017

That's fair enough Mike but the AA man said "abs sensors are down on all four wheels" - so I presume this means there were 4 specific codes picked up pertaining to faults the ABS ECU detected with the wheel sensors. This would mean that the 3 Amigos were correctly being displayed by the dash and that was not a networking problem.

This is all (semi-educated) guess work, but the 4 codes are not going to be randomly generated - the only way they can be generated is if the ECU detects what it thinks is a problem with the sensors. The AA guy is absolutely right in that the 4 sensors are not going to fail at the same time, so why did the ECU generate those codes? It does not use the network to detect sensor faults - that input comes in on the 4 (or 8) wires directly from the sensors to pins on the ECU. I'm thinking the alternator is pumping incorrect currents through the electronics that the ECU detects as faults in the sensors. These currents being out of spec would also cause problems for the other systems.

I have to say though, that if the currents were so far out of spec that the ECUs were detecting faults in sensors - I'm not sure how the ECUs themselves would continue to operate - which would sort of question how the engine managed to carry on running smoothly!

Skinny Mike · Feb 8, 2017

GrumpyGel said:
That's fair enough Mike but the AA man said "abs sensors are down on all four wheels" - so I presume this means there were 4 specific codes picked up pertaining to faults the ABS ECU detected with the wheel sensors. This would mean that the 3 Amigos were correctly being displayed by the dash and that was not a networking problem.

This is all (semi-educated) guess work, but the 4 codes are not going to be randomly generated - the only way they can be generated is if the ECU detects what it thinks is a problem with the sensors. The AA guy is absolutely right in that the 4 sensors are not going to fail at the same time, so why did the ECU generate those codes? It does not use the network to detect sensor faults - that input comes in on the 4 (or 8) wires directly from the sensors to pins on the ECU. I'm thinking the alternator is pumping incorrect currents through the electronics that the ECU detects as faults in the sensors. These currents being out of spec would also cause problems for the other systems.

I have to say though, that if the currents were so far out of spec that the ECUs were detecting faults in sensors - I'm not sure how the ECUs themselves would continue to operate - which would sort of question how the engine managed to carry on running smoothly!

I don't disagree with what your saying, but if the ABS ECU is duff, it could quite easily generate 4 duff wheel sensor codes, as it's not relaying the info from them through the canbus.
The canbus system is a marvelous thing, until one part of it stops working, then it fails to report correctly, giving the spurious codes.
It's all guess work though. Unless we were stood in front of this gents Freelander with hands on, we really don't know

Mike

Madmustang · Feb 10, 2017

gerald123 said:
hi ,hope someone can help...i have had my Freelander diesel td4 for a month,now the ......abs/ hdc/ tc/ brake/ srs/ and engine management light are staying on while i am driving ... and speedo not working.sometimes i have noticed my brake light on dashboard will go off ...and then my speedo starts working ......but the car runs normal and pulls well.....can someone help please.

Have you or anybody else done any work in the engine bay at all?

gerald123 · Feb 10, 2017

Madmustang said:
Have you or anybody else done any work in the engine bay at all?

all seems ok now thanks,I put... new dashboard cluster in and took car for a good hours run and all lights have now gone off...and have not returned, just hope it stays that way...... thank you all for your help,will keep you informed.

dashboard warning lights staying on.

GrumpyGel

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Skinny Mike

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GrumpyGel

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Skinny Mike

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Madmustang

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gerald123

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