Trio of Lovely Dash Lights.......

C

Callahan

Member
My love/hate relationship with the Zed continues and I'm fresh back from the garage after having the "trio of warning lights" issue resolved! Just posting this as it may be of use to anyone experiencing similar issues.
After removing my 18" 107's for refurb the bodyshop threw on a set of 17's so that I could get the car home while they did the wheels in their own time. After driving about 20 feet the DSC/ABS and handbrake light all came on in orange. I thought that maybe the different wheel size may be the issue so wasn't overly concerned but upon refitting the original wheels the lights remained on!

The symptoms were exactly this -
Upon starting the car all lights would remain lit.
After moving about 10 feet all lights would turn off.
As soon as the car reached 20mph all lights would come on, accompanied by a warning beep.

Having read several threads here I was fearing the worst and presumed it was the ABS/DSC pump, but luckily for me it turned out to be the N/S front speed sensor. Apparently when you first start the car it sends a pulse/check to the DSC pump, hence the lights turning off when you pull away, however the car needs to get to 20mph to check the wheel speed sensors! Another helpful fact is knowing that the pump doesn't run continually so by simply feeling it you can't tell whether it's functioning properly or not. It only kicks in when either the ABS or traction control calls upon it.
I'm still not convinced that the wheel changes didn't have something to do with it, but the N/S front brake calliper had also been binding so perhaps a build up of heat affected the sensor?

A really helpful set of typical dash error light combinations was posted by ph001 (Hope you don't mind me posting them here!)

1) DSC + ABS = ABS pump.
2) DSC + handbrake (in yellow) = pressure sensor
3) DSC + ABS + handbrake (in red) = wheel speed sensor.
4) DSC + ABS + handbrake (in yellow) + tyre pressure = wheel speed sensor.
5) DSC + ABS + handbrake (in yellow) = steering angle sensor fault / ABS pump.
6) DSC permanently on = steering angle sensor calibration issue / yaw sensor / lat accel sensor.

Hope this can be of use!
 
A slightly dodgy wheel bearing can be the problem. It can result in damage to the speed sensor. My Z4C did the three light thing after I had reversed out of a tight space on full lock, which caused a slight clonk noise, which I think was slight movement on the wheel bearing allowing the sensor get damaged.
 
Callahan said:
1) DSC + ABS = ABS pump.
2) DSC + handbrake (in yellow) = pressure sensor
3) DSC + ABS + handbrake (in red) = wheel speed sensor.
4) DSC + ABS + handbrake (in yellow) + tyre pressure = wheel speed sensor.
5) DSC + ABS + handbrake (in yellow) = steering angle sensor fault / ABS pump.
6) DSC permanently on = steering angle sensor calibration issue / yaw sensor / lat accel sensor.

Hope this can be of use!
Click to expand...

I've got another combination but haven't got to the bottom of it yet.
DSC + handbrake (in yellow) + tyre pressure

Similar to 4 above but without the ABS.

They're not always showing either. 95% of the time they are on but occasionally they disappear on start up and stay off until the next start up.

I've replaced the pressure sensors on the master cylinder as that were cheap and easy to do and then had the codes cleared but no improvement.

Any ideas?
 
Hmmm, I wonder if the TPS warning is just a genuine tyre pressure issue so a bit of a red herring. Have you actually checked all tyre pressures and reset the TPW? I can't imagine any scenario of duff sensors that affects the TPW but not the ABS?????
 
ph001 said:
Hmmm, I wonder if the TPS warning is just a genuine tyre pressure issue so a bit of a red herring.
Click to expand...

Could be, as I have a very slow puncture on OS rear. 4 to 6 weeks to loose 5 psi.

I've checked the pressures but it won't allow a reset while the 3 lights are on and the TPS light is out when the other 2 are not lit. Having said all that and recounting my previous post here's my latest thoughts.

The sensors were only replaced and codes cleared this morning, car started at the garage and driven home with no lights. Car started again - lights on, taken out shopping, for lunch etc. and lights stayed on, ignition off and on a couple of times without starting the engine and the lights are randomly on and off. I then wrote the post above.

This afternoon I've driven it again and the lights are out and stayed out for a quite a few starts and stops. Could it be that there was a slight air bubble in one of the new sensors that has now cleared? Fingers crossed!
 
Could be air in one of the pressure sensors I suppose but that shouldn’t bring the tpw light on.

How old is your battery?
 
ph001 said:
Could be air in one of the pressure sensors I suppose but that shouldn’t bring the tpw light on.

How old is your battery?
Click to expand...

The TPS light can't be reset with the other two on - so it may still be a red herring? The battery is a Bosch, replaced last year in an attempt to get rid of other faults. So it is good. My wife is driving the car some distance today so she'll report how it went later on.
 
'V' drove it today. Lights out on start up and for 35 miles then came on during a slow sharp RH turn. Stayed on until end of journey. Came on on restarting and stayed on until she came home.
I drove it this afternoon.
Lights on on start up but went out while reversing from the drive. Stayed out for 2 miles and then came on while parking.
Lights out on start up and stayed out for a further 5 miles to a mate's house.
Lights on on startup. Stopped engine and restarted..... lights out for the 5 miles home.
Parked in drive and stopped engine and restarted....lights on. Stopped engine and restarted ... lights on. Stopped engine and restarted.... lights off! I didn't move the car during this or press the brakes.
 
I think you are going to have to put a code reader on it. Usually when they are very intermittent like that it is abs sensor, abs pump, steering angle sensor or pressure sensor in master cylinder. Trouble is they don’t really fit the lights you have. I’d wager a small bet on steering angle, yaw or lateral accel sensor (no.6 in my table).
 
Code reader has been on it a couple of times. First time the pressure sensors in the master cylinder were replaced. Next time no codes stored. I've been having intermittent alarm problems which are not related to the bonnet switch so could be the yaw sensor.

I guess that this is the one?

sensor.jpg
 
Yep, that’s the one. It’s a bit of a stab in the dark to be honest but without any codes what else can you do??? Weird how it’s not storing anything, this sure is a strange one.
 
I'm leaning towards the yaw sensor idea as being the problem. The new pressure sensors certainly have affected the regularity of the problem in that the lights now seem to follow a pattern rather than on almost permanently.

'V' drove the car again today with lights out until she went over a speed hump while turning right...... lights on. Switched off the engine and restarted... lights out... until 20 miles later coming in our drive where there is a slight dip and rise while turning left..... lights on.

I'm tempted to buy a second hand sensor just to try it out. Whereabouts is it located and how difficult is it to replace?
 
Well...... problem solved. I removed the hardtop!! There must have been a intermittent connection to the HRW on the hardtop as some times it wouldn't work at it's best. This must have caused some sort of current flow in the same circuit as the sensors and threw up a false fault code. I've been running for a week or so without a hardtop and without any lights.

I was waiting until I had the hardtop off to allow access to remove the driver's seat and replace the yaw sensor cluster, looks like I don't need to do that now.
 
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