I basically like this car, but have had nothing but fault lights since I got it. Now comng up to MOT...
Any advice would be much appreciated and might save my sanity!
1) ABS
ABS light comes on sometimes in journey (sometimes goes out again) sometime does not go off at startup sometimes fine for two days in a row. ABS seems to work fine though! Garage said it was the ABS ECU. Had this changed for a tested second-hand one - still just the same. Also checked over/ cleaned the big plug to the ABS ECU. Looks fine, no corrosion or dodgy wires.
2) Engine light (not spanner)
Comes on about once a week and when it does the air con seems to 'warm up' - still works but not very well (normally very good). I have a memoscan fault code reader, it sees there is a fault but I get the code NA (not available?). The reader can reset the fault light and then everythng is fine.
I found a tip that if you turn on the ignition (not start the engine!) with brake and accelerator both down you get a flashing readout on the fault light which I do. I think it reads 10, 1, 1, 5, 1 but I have no idea if this means anything or how to interpret it.
Help!
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Re: ABS - have you had the wheel sensors checked / tested?
2) Engine light (not spanner) Comes on about once a week - I think it reads 10 1 1 5 1
I think you've got one too many "1's" there.
Possibly P0151 or P0115
The engine light is the emissions fault light.
P0151 code = Oxygen O2 Sensor Circuit Low Voltage (www.obd-codes.com/p0151 )
Most likely culprit will be the lambda sensor. Not sure why the AC temp changes though.
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Thanks Dave,
Took the car to my local garage, so I hope they eliminated the wheel sensors. They said the code indicated a faulty valve relay and could only be the ECU, but this does not seem to be the whole story. Would wheel sensors give me the fault when the car is stationary - this sometimes happens. I can't tell what code it is giving me now, as I can't read them - the ABS outputs to a different pin on the diagnostic socket and it seems you need a pretty fancy reader to check this.
I'll check the 'flashing' fault code again, but I'm pretty sure I read it right. I've only seen this tip in one place, think it only applies to a narrow range of models - apparantly some give you the code readout on the odometer, which would be nice...
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OK! Have discovered that 10 flashes=0, so the fault code I'm getting is
0 1 1 5
Can any kind soul tell me what this means, all the tables I've looked at start at number 0200 - is this a Vauxhall code and not OBD?
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The codes generally start with "P"
P0115 Engine Coolant Temperature Circuit High Input C-11
P0115 Engine Coolant Temperature Circuit Low Input C-11
P0115 Engine coolant temperature circuit malfunction C-11
www.vauxhallownersnetwork.co.uk/showthread.php?t=3...8
Edited by Dynamic Dave on 19/07/2009 at 19:50
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Thanks again Dave,
Guess I'll start looking at the wiring and the temp sensor - anyone had anything like this?
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based on my limited knowledge of only the ABS on a Citroen BX.....
If a wheel sensor (or the connecting cable) are open circuit on start up the ABS system will detect a fault and illuminate the fault indication (probably fails to initialise the complete system). So possible cable sensor fault?
However you have said that the ABS works? is that when the light is on?
Could the garage description of ' faulty valve relay' actually mean an actuator/solenoid? fault on the ABS hydraulic unit (not the ECU)?
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Hi pmh3
Yes, the ABS seems to work, even when the light is on!
Yes, I was wondering if the fault could be in the block whcih contains the valves. The garage only changed the ECU, although I gave them the whole lot. When you remove the ecu, the only electrical connection to the valve block is a 2 pin spade connector to (I assume) the hydraulic modulator. 8 encased coils slip over 8 studs on the unit, which I assume are magnetically operated valves of some kind. However as there appears to be no electrical feedback from these valves to the computer, I can't see how the ECU could detect a fault in them.
Does anyone know how this unit actually works? Might help me understand what is going on...
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okay bear with me on this one when the abs light is on the abs is in fact turned off, that said if the brake lights fail the abs light comes on on the dash, afaik you are not suppose to split the control unit and modulator they are supposed to be fitted complete, if the garage diagnosed the ecu at fault and put one on that you supplied complete then they poorly diagnosed it in the first place and have not done the job correctly (buy just fitting the ecu part),the abs ecu also has an overcharge system to protect it from the alternator from damaging it so next time the light comes on you need to check the brake lights are working and see what the alternator output is 14.5 volts at its maximum
the way descibed above is the correct operation, ing on, system self checks, if it see's all the correct resistances etc then the light will go out (even if one of the speed sensor rings is split/broken)if the ecu then see's a wheel doing a different speed under normal driving ie driving not brakeing then it will put the light on (usual failure mode for these motors is a sensor ring split, the ring gets rust between it and the cvjoint and sweels up and breaks /splits the ring)this is a possibility with your vehicle may be worth a good look at the ringsand the distance between ring and sensor (air gap), if the light is still coming on and you have checked all of the above then its back to the garage for a code read hopefully for free as the garage have not repaired it correctly, Regards TB
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From a purely theoretical point of view, it would be possible for the ECU to check
1. the continuity of each of the modulator coils (easy)
2 the magnetic characteristics of each modulator coil, ie how does the inductance change when the coil is enegised sufficiently to operate the valve cf the inductance at very low current.
I do not know if it is smart enough to actually do this, but certainly a possibility.
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