Strange Instrument Cluster Issue

[vangara]

Hi All

I am having a strange issue on my 2005 VZ, while driving the car normally, the analog meters(Speedo, RPM, Temp, Fuel) in the instrument cluster go off (fall to the "no-reading" position) and the AIRCON goes off too, but the engine keeps running as usual, even with the cruise control on. The first error that I get is ABS Fault, then I see the hand brake sign continuously on, if I continue to run the car in the same condition I some time see "reduced performance" and some transmission related errors. But if the car is pulled-over with engine running and the gear in Neutral, everything goes back to normal.

I noticed that there is a reading in the trip computer called "ADC BRAKE Reading" and this issue happens every time the reading goes above 2.5. I have to pull-over and change to neutral for a few seconds to bring down the ADC brake reading, then the analog meters start working. We are stumped, unable to trace the issue for the last one month, I have seen similar issues reported in these forums but there are no clear pointers and the gentleman who started the thread dint mention if it was resolved or how it was resolved?

Nothing on tech2.

Did any one of you come across such issue? Any help appreciated.

 

[Benboy]

Suggest you find a reputable Auto Mechanic or better still, join an Auto Club (RACV, NRMA etc) they provide diagnostic services at their Workshops for a nominal fee. One way to get an unbiased report.

 

[petern64]

I had a commodore do a similar thing, ended up being a faulty alternator,check yours out !

 

[vangara]

I had a commodore do a similar thing, ended up being a faulty alternator,check yours out !

Thanks for the reply Peter, alternator was the first thing we checked, found nothing wrong with it. Could it be related to ABS, that is the first fault thrown, but my mechanic does not believe so. I believe it is somehow related to brakes, does any know what this "ADC Brake Reading" is?

 

[vangara]

@Petern64, you were spot-on, it is indeed the alternator.

While the car was stationary the output from the alternator was ~13.8V, but with tech2 connected and the car running (while in gear) it sometimes shot up to 18V+, and everything died. We could see the alternator related logs in Tech2, it will be sorted in a couple of hours, thanks all for the help.