4WD light!!!
- Thread starter skendrick
- Start date
Dave Wilkinson
New member
Steve,
This is one of those problems that can have a multitude of logical causes - and quite a few illogical ones too. The most obvious things to check are battery voltage and hydraulic fluid level since the PDAS system is particularly critical on both.
One of the most common illogical causes of this type of problem is high voltage ignition leakage causing the ABS/PDAS systems to go berserk. Bad coils and/or distributor caps and rotors were the cause on my car which took more than a year to diagnose!!
Try the easy/cheap stuff first before you spend out loads of potentially unnecessary money.
Regards
Dave
This is one of those problems that can have a multitude of logical causes - and quite a few illogical ones too. The most obvious things to check are battery voltage and hydraulic fluid level since the PDAS system is particularly critical on both.
One of the most common illogical causes of this type of problem is high voltage ignition leakage causing the ABS/PDAS systems to go berserk. Bad coils and/or distributor caps and rotors were the cause on my car which took more than a year to diagnose!!
Try the easy/cheap stuff first before you spend out loads of potentially unnecessary money.
Regards
Dave
marlin
New member
Had this problem with my 964, the 4 wheel drive light came on with an alarm sound, mainly when going over a bump or uneven surface on the motorway. Lost count of the times it went into the dealers in Leeds. They never sorted it but managed to remove much tread from the tyres with the constant road testing [
]
When they gave up, so did I and traded in []
Sorry not very helpful, maybe diagnostics have moved on from the nineties
]When they gave up, so did I and traded in [
]Sorry not very helpful, maybe diagnostics have moved on from the nineties
Steve,
I had a similar problem a few years back when the 4WD light came on as I drove over a particularly bumpy surface in road works. Adrian Streather had posted much info regarding this on the Rennlist technical site, one comment being that if the PDAS/ABS warning light comes on intermittantly, then this is usually due to a dynamic component failure (ie one that needs movement) such as a speed sensor or acceleration sensor.
From his various postings of info I decided to check the speed sensors on the rear wheels and found that the plastic case holding one had popped open and it was therefore not reading correctly. A simple job of clipping it shut adain solved the problem.
As Dave said, it could be due to a number of problems, but I would recommend looking at Adrian's info on the Rennlist technical forum, you might be lucky too and find it's somthing simple.
Regards,
Mike
I had a similar problem a few years back when the 4WD light came on as I drove over a particularly bumpy surface in road works. Adrian Streather had posted much info regarding this on the Rennlist technical site, one comment being that if the PDAS/ABS warning light comes on intermittantly, then this is usually due to a dynamic component failure (ie one that needs movement) such as a speed sensor or acceleration sensor.
From his various postings of info I decided to check the speed sensors on the rear wheels and found that the plastic case holding one had popped open and it was therefore not reading correctly. A simple job of clipping it shut adain solved the problem.
As Dave said, it could be due to a number of problems, but I would recommend looking at Adrian's info on the Rennlist technical forum, you might be lucky too and find it's somthing simple.
Regards,
Mike
skendrick
New member
Thanks Mike,
I checked the Rennlist website and then checked my brake fluid level as a first port of call.
My fluid level was near the minimum level, so I topped it up and now the light doesn't come on any more.
I think it works now, but I am also having fun in the snow sliding the back around (at all of 10mph).
Living in Reading we have had lots of snow in our close, so far the porsche is the only one that's managed to get out to get supplies.
Most of the neighbours have new'ish cars but couldn't get up the slight incline to the main road (not that that's bean salted either!).
They didn't think the Porsche would do it but she drove straight out and back down again without any problem.
We all went out on Wednesday and cleared the road but more snow came down that night, so we gave up (Picture attached).
I checked the Rennlist website and then checked my brake fluid level as a first port of call.
My fluid level was near the minimum level, so I topped it up and now the light doesn't come on any more.
I think it works now, but I am also having fun in the snow sliding the back around (at all of 10mph).
Living in Reading we have had lots of snow in our close, so far the porsche is the only one that's managed to get out to get supplies.
Most of the neighbours have new'ish cars but couldn't get up the slight incline to the main road (not that that's bean salted either!).
They didn't think the Porsche would do it but she drove straight out and back down again without any problem.
We all went out on Wednesday and cleared the road but more snow came down that night, so we gave up (Picture attached).
asjasj
New member
Both times I took my C4 out yesterday, following cold starts I got the warning lights on. Return journeys when the car was warmed up it was fine. I put this down to stress on the battery starting a cold car. From past experience if I charge the battery (in my case) it solves the 'problem'.
Was interesting to be able to brake harder than is sensible on snow and feel the difference with and without ABS anyway!
Ade
Was interesting to be able to brake harder than is sensible on snow and feel the difference with and without ABS anyway!
Ade
had major scare in the snow tonight! leaving a friends estate, just crawling along in 2nd. braked and the ABS kicked in but didn't slow down much! then the ABS switched off as the speed dropped to under 5mph but the car speeded up as the wheels locked... I had to pump the pedal to stop but still ended up in the middle of the main road in front of a car!
The only saving grace was the fact that the car started to slide right, so the oncoming car realised something was wrong befoe I slid out in front of him and slowed down in time to go round me. Pulse rate has only just dropped to near normal levels now that the car is back safe in its parking space.[&o]
The only saving grace was the fact that the car started to slide right, so the oncoming car realised something was wrong befoe I slid out in front of him and slowed down in time to go round me. Pulse rate has only just dropped to near normal levels now that the car is back safe in its parking space.[&o]
MarkK
Active member
Took ours(1990C4) out today it was about +2 degrees,no lights at all,no alarms the other day when it was -2 degrees the lights were on i got a peeping alarm and the ABS stopped working,this is very deffo temp related.Hydraulic fluid reducing in volume with the lower temps?Tyre pressure reducing throwing off the sensors?[8|]
PS Martin that sounded close no harm done though TG!
PS Martin that sounded close no harm done though TG!
Porker993
New member
When I had my 964 C4, my 4WD/ABS warning light used to come on every morning for a few minutes after I started the car. Once the hydraulic pump had got up to pressure, the light went out, and I was happy enough with that. After a few years of ownership, the light took longer and longer to go out. Eventually it used to come on randomly during normal driving, sometimes accompanied by a bleeping noise from the dashboard.
I was told that the hydraulic brake booster pump was on its way out, due to faulty seals, and would need replacing at a cost in those days (2002) of approx £1,000. I was told this was a common fault with C4s.
This coincided with me selling the car.
I was told that the hydraulic brake booster pump was on its way out, due to faulty seals, and would need replacing at a cost in those days (2002) of approx £1,000. I was told this was a common fault with C4s.
This coincided with me selling the car.
Dave Wilkinson
New member
Nick,
The ABS/PDAS system on the C4 has always been accessible by a "hammer" - it's the solely ABS system fitted to the C2 which cannot be accessed.
Mark,
The extended settle time for the hydraulic pressure is often attributable to the system needing a bleed. A recent primary bleed on my C4 reduced the pump time from 90 seconds down to little more than 15. It's a lot cheaper than a new pump!!!
Regards
Dave
The ABS/PDAS system on the C4 has always been accessible by a "hammer" - it's the solely ABS system fitted to the C2 which cannot be accessed.
Mark,
The extended settle time for the hydraulic pressure is often attributable to the system needing a bleed. A recent primary bleed on my C4 reduced the pump time from 90 seconds down to little more than 15. It's a lot cheaper than a new pump!!!
Regards
Dave
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