PDAS/ABS light on, no charging
12-03-2006, 05:29 PM
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PDAS/ABS light on, no charging
I've had my 1990 C4 for less than 2 months. I have noticed that sometimes when starting, the ABS and PDAS light will stay on until reaching 3000 RPM.
A few days ago i just took off driving for a few minutes without reving past 3000 RPM. Then suddenly the car hesitated, almost stopped. I just stamped the pedal to the floor and the car picked up and cleaned.
I have read in Adrian Streathers book page 397 that this indicates that the PDAS control unit registrates a voltage lower than 9,9 volt.
Then i charged my battery overnight, guessing that only small trips for a while with heaters on had discharged the battery too much. Measured the battery voltage to 12,3 volt before and 12,53 volts afterwards. Started the car. ABS/PDAS lights still on.
Measured the battery voltage witj the car idling. What happens is that the alternator does not start to charge until the ABS/PDAS lights go off reaching 3000 RPM. That was the reason the car hesitated the other day. The voltage was dropping to a critical level. The battery is one year old, and a green led on the battery is showing OK. Measured the battery voltage with alternator charging. 13,7 volt from idle and up.
As i said this only occur now and then.
Is there anything wrong? Is there a cutout relay beetween alternator and battery that could be the problem?
Odd Gunnar Moe
Norway
A few days ago i just took off driving for a few minutes without reving past 3000 RPM. Then suddenly the car hesitated, almost stopped. I just stamped the pedal to the floor and the car picked up and cleaned.
I have read in Adrian Streathers book page 397 that this indicates that the PDAS control unit registrates a voltage lower than 9,9 volt.
Then i charged my battery overnight, guessing that only small trips for a while with heaters on had discharged the battery too much. Measured the battery voltage to 12,3 volt before and 12,53 volts afterwards. Started the car. ABS/PDAS lights still on.
Measured the battery voltage witj the car idling. What happens is that the alternator does not start to charge until the ABS/PDAS lights go off reaching 3000 RPM. That was the reason the car hesitated the other day. The voltage was dropping to a critical level. The battery is one year old, and a green led on the battery is showing OK. Measured the battery voltage with alternator charging. 13,7 volt from idle and up.
As i said this only occur now and then.
Is there anything wrong? Is there a cutout relay beetween alternator and battery that could be the problem?
Odd Gunnar Moe
Norway
12-03-2006, 05:44 PM
#2
Sounds like a problem with the cold solder joints on the back of the clock.
Try this thread for starters. It talks about the 3k rpm limit. The number of warning lights in the clock and the leads that go to it are known for causing problems such as the one you describe.
Cheers,
Dave
Try this thread for starters. It talks about the 3k rpm limit. The number of warning lights in the clock and the leads that go to it are known for causing problems such as the one you describe.
Cheers,
Dave
12-03-2006, 06:25 PM
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Be sure to re-solder contacts on both sides of the PC board.
I had my clock out a few weeks ago. I took it apart as described in the thread. I re-soldered the contacts on the inside of the board. The symptoms continued. Taking the clock out again, looking at the contacts on the outside of the board revealed several cold solder joints I had not noticed the first time. Duh...
Fixed that, everything is back working just fine.
Danz C4.
I had my clock out a few weeks ago. I took it apart as described in the thread. I re-soldered the contacts on the inside of the board. The symptoms continued. Taking the clock out again, looking at the contacts on the outside of the board revealed several cold solder joints I had not noticed the first time. Duh...
Fixed that, everything is back working just fine.
Danz C4.
12-05-2006, 12:22 PM
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I definitely concur with the clock theory.
Had the identical problem but cured it in a different way;
as I'm not too expert in the soldering dept I found a 993 clock on ebay for just £20.00 sterling.
Less than five minutes work to swap them over and problem resolved!
David
'91 C4
Had the identical problem but cured it in a different way;
as I'm not too expert in the soldering dept I found a 993 clock on ebay for just £20.00 sterling.
Less than five minutes work to swap them over and problem resolved!
David
'91 C4
01-22-2007, 04:56 AM
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Took out the clock and resoldered on both sides of the print. Could not measure any cold solder joints. However after 6 weeks there is no sign of the problem. The PDAS and ABS lights will disappear within 20-30 seconds after startup even if the car just idles. Seems that the problem is fixed. 
Odd Gunnar Moe
Odd Gunnar Moe