ABS and Differential Light coming on in dash
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Hi,
The weather has begun to dry up here in Ireland eventually so i decided to taken my 90 C4 964 out for a drive (parked in shed for last couple of months), just last night while i was driving the car the ABS and Differential lights came on simultaniously on the dashboard with the buzzer noise also activated, upon seeing and hearing this i pulled over and turned off ignition, i left the car off for about 5 minutes and then started it again and everything was ok, however again today after maybe driving 11-15 miles the two lights came on again!
Can anyone help me out here with what might be causing this problem?
Any help or advice would be greatly appreciated, thanks in advance
Regards,
Nelius
Ireland
The weather has begun to dry up here in Ireland eventually so i decided to taken my 90 C4 964 out for a drive (parked in shed for last couple of months), just last night while i was driving the car the ABS and Differential lights came on simultaniously on the dashboard with the buzzer noise also activated, upon seeing and hearing this i pulled over and turned off ignition, i left the car off for about 5 minutes and then started it again and everything was ok, however again today after maybe driving 11-15 miles the two lights came on again!
Can anyone help me out here with what might be causing this problem?
Any help or advice would be greatly appreciated, thanks in advance
Regards,
Nelius
Ireland
#3
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This *could* be a serious problem, so please look carefully at your hydraulic pump circuit before driving.
I don't mean to be alarmist, but the hydraulic system is integral to braking and alarms in this circuit could be serious. Your problem could be very simple, but better safe than sorry.
In particular, check the front boot area, under the carpet and under the spare tire to determine if the pressure switch on your hydraulic pump is leaking. If so, you could end up without brakes. Rather quickly, I might add! The switch, itself, can be replaced.
If the switch is faulty and the pump runs continuously you could also overheat the pump resulting in the need for a replacement; which is very expensive. The switch is not very expensive.
Of course, it could be as simple as being a bit low on the brake/hydraulic fluid reservoir. However, a combination of both the lights and the horn is the maximum warning alarm, so you should take care to diagnose what's happening.
Here are some notes (and thread ref's) to get you started:
I don't mean to be alarmist, but the hydraulic system is integral to braking and alarms in this circuit could be serious. Your problem could be very simple, but better safe than sorry.
In particular, check the front boot area, under the carpet and under the spare tire to determine if the pressure switch on your hydraulic pump is leaking. If so, you could end up without brakes. Rather quickly, I might add! The switch, itself, can be replaced.
If the switch is faulty and the pump runs continuously you could also overheat the pump resulting in the need for a replacement; which is very expensive. The switch is not very expensive.
Of course, it could be as simple as being a bit low on the brake/hydraulic fluid reservoir. However, a combination of both the lights and the horn is the maximum warning alarm, so you should take care to diagnose what's happening.
Here are some notes (and thread ref's) to get you started:
Code:
- Hyrdraulic Pump Pressure Switch Indications Warning lights on lights on oil temp/press gauge ! master alarm light #8 4wd system light (upper right; 4 wheels and trans diag) #13 brake pressure light (bottom center; upper right of cluster; brake pads w/ ! in center) Beeper gong relay (?) this is a low pressure indicator STOP, TURN OFF CAR if pressure goes too low you can loose bakes and/or run the pump dry and destroy it Diagnostics Wait until system finishes pressurizing lights should go out in ~40 secs after starting car should hear pump running don't let it run more than a couple of minutes; will overheat Low fluid should be full up Fuse #15 (18?), 40amp - hydraulic pump check and/or replace Relay #51 Ground points remove and clean all ground points in front trunk Clock cold solder joint problem sometimes lights go out when rev's reach 3000 this is a charging system ciruit malfunction due to solder joints should have charging light on, as well Pressure switch seal Pressure switch Pump Parts 999.707.094.40 Rubber O-Ring 964.606.904.00 Pressure Sensor 964.615.135.00 Relay hyd pump 993.355.953.01 Part number Smith Motorworks (ebay) has this pump (says 993 part) for $1500 http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&refid=store&category=42605&viewitem=&item=190000002658 Links Pump Repair - dynatechcorp_com http://stores.ebay.com/DynaTech-Corp...QQftidZ2QQtZkm C2/C4 Technical Stuff http://www.ncweb.com/~rochford/tech.htm Threads Hydraulic Brake Pump Failure Stiff brake pedal - No braking! Methodical C4 Hydraulic Pump 964 C4 Hydraulic pump leakage Problems with the high pressure hydraulic system The 89-94 964 C4 pump Total brake failure....without WARNING!!!! C4 PDAS/ABS Update Brake problem only 964? Warning lights on this morning Best source for PDAS pump and/or pressure switch? Assisted Breaking Failure PDAS & Brake warning light and Buzzer *FIXED* Loud buzzing from ABS unit ABS Problem ABS pump stays on ABS failure Brake failure - leak at ABS pump New owner / abs/4wd warning light PDAS/ABS warning - a solution
Last edited by dfinnegan; 02-07-2010 at 11:55 AM. Reason: turned the thread ref's into links
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Thanks guys for your responses,
On my way home yesterday (after posting my message) to put the car back in storage, another strange thing happened, as i was entering my house all the lights in the dash board came on along with the buzzer (same as when you turn the key in ignition, with the exception of the buzzer) however the car was still runnig and did not cut out at any point, i am now begining to wonder if it is an electrical problem i am having (new battery put in car this week only). Could the altenator be acting up and causing this to happen?, i will still check my brake fluid levels tonight though.
As you can well appreciate Ireland is not a wash with Porsche dealers or Mechanics so it is hard to get problems solved over here.
Regards,
Nelius
Ireland
On my way home yesterday (after posting my message) to put the car back in storage, another strange thing happened, as i was entering my house all the lights in the dash board came on along with the buzzer (same as when you turn the key in ignition, with the exception of the buzzer) however the car was still runnig and did not cut out at any point, i am now begining to wonder if it is an electrical problem i am having (new battery put in car this week only). Could the altenator be acting up and causing this to happen?, i will still check my brake fluid levels tonight though.
As you can well appreciate Ireland is not a wash with Porsche dealers or Mechanics so it is hard to get problems solved over here.
Regards,
Nelius
Ireland
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Will check this when i go home from work this evening, will keep you posted on the outcome (fingers crossed its only a small problem like that)
Regards,
Nelius
Ireland
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Hi dfinnegan,
Do you think that the two issues above could be related, i.e the lights for the ABS and Differential coming on ocassionally since i put in the new battery (during the weekend) along with the "Christmas Tree Effect" ?
Regards,
Nelius
Ireland
Do you think that the two issues above could be related, i.e the lights for the ABS and Differential coming on ocassionally since i put in the new battery (during the weekend) along with the "Christmas Tree Effect" ?
Regards,
Nelius
Ireland
#13
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I wouldn't expect a relationship between hydraulic issues and the christmas tree light show.
Conversely, it seems possible that the christmas tree effect could give rise to hydraulic warnings; although I don't recall that manifestation being reported on the board before.
I had my hydraulics fail due to a leaking pressure switch and the event left a strong impression on me.
That said, these cars are very sensitive to stray voltage/current and all sorts of things can occur from poor running and missing, to stray warning lights.
One of the smart folks here once posted and asked "what's changed recently". That makes a lot of sense to me so I suggested the battery checks. Some folks have reported bad ground wires even though they measured out okay with a mulit-meter, so changing the battery seems suspect.
Still, do look at the hydraulic fluid level, look for leaks and measure the time to prime the pump on initial key ignition. It should run ~40 secs, or less after sitting for a day, or so. And the pump should turn off. I can easily hear mine, but I'm sensitive to it. Note that if the pump runs an minute, or so, it's not alarming, but does point to potential issues. That could be as simple as a fluid flush requirement.
Best of luck diagnosing. Keep the info flowing as there are lots of very knowledgeable people on this board and they are very willing to jump in and help out fellow enthusiasts.
Cheers
Conversely, it seems possible that the christmas tree effect could give rise to hydraulic warnings; although I don't recall that manifestation being reported on the board before.
I had my hydraulics fail due to a leaking pressure switch and the event left a strong impression on me.
That said, these cars are very sensitive to stray voltage/current and all sorts of things can occur from poor running and missing, to stray warning lights.
One of the smart folks here once posted and asked "what's changed recently". That makes a lot of sense to me so I suggested the battery checks. Some folks have reported bad ground wires even though they measured out okay with a mulit-meter, so changing the battery seems suspect.
Still, do look at the hydraulic fluid level, look for leaks and measure the time to prime the pump on initial key ignition. It should run ~40 secs, or less after sitting for a day, or so. And the pump should turn off. I can easily hear mine, but I'm sensitive to it. Note that if the pump runs an minute, or so, it's not alarming, but does point to potential issues. That could be as simple as a fluid flush requirement.
Best of luck diagnosing. Keep the info flowing as there are lots of very knowledgeable people on this board and they are very willing to jump in and help out fellow enthusiasts.
Cheers
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I wouldn't expect a relationship between hydraulic issues and the christmas tree light show.
Conversely, it seems possible that the christmas tree effect could give rise to hydraulic warnings; although I don't recall that manifestation being reported on the board before.
I had my hydraulics fail due to a leaking pressure switch and the event left a strong impression on me.
That said, these cars are very sensitive to stray voltage/current and all sorts of things can occur from poor running and missing, to stray warning lights.
One of the smart folks here once posted and asked "what's changed recently". That makes a lot of sense to me so I suggested the battery checks. Some folks have reported bad ground wires even though they measured out okay with a mulit-meter, so changing the battery seems suspect.
Still, do look at the hydraulic fluid level, look for leaks and measure the time to prime the pump on initial key ignition. It should run ~40 secs, or less after sitting for a day, or so. And the pump should turn off. I can easily hear mine, but I'm sensitive to it. Note that if the pump runs an minute, or so, it's not alarming, but does point to potential issues. That could be as simple as a fluid flush requirement.
Best of luck diagnosing. Keep the info flowing as there are lots of very knowledgeable people on this board and they are very willing to jump in and help out fellow enthusiasts.
Cheers
Conversely, it seems possible that the christmas tree effect could give rise to hydraulic warnings; although I don't recall that manifestation being reported on the board before.
I had my hydraulics fail due to a leaking pressure switch and the event left a strong impression on me.
That said, these cars are very sensitive to stray voltage/current and all sorts of things can occur from poor running and missing, to stray warning lights.
One of the smart folks here once posted and asked "what's changed recently". That makes a lot of sense to me so I suggested the battery checks. Some folks have reported bad ground wires even though they measured out okay with a mulit-meter, so changing the battery seems suspect.
Still, do look at the hydraulic fluid level, look for leaks and measure the time to prime the pump on initial key ignition. It should run ~40 secs, or less after sitting for a day, or so. And the pump should turn off. I can easily hear mine, but I'm sensitive to it. Note that if the pump runs an minute, or so, it's not alarming, but does point to potential issues. That could be as simple as a fluid flush requirement.
Best of luck diagnosing. Keep the info flowing as there are lots of very knowledgeable people on this board and they are very willing to jump in and help out fellow enthusiasts.
Cheers
i really appreciate all the help and information you have given me, its not easy to get info on Porsches over here in Ireland, so i am greatfull to you and all the Rennlisters for any words of wisdom that can be put my way.
Regads,
Nelius
Ireland
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I'm signing on to this.
I'm having the very same issue(s).... Mine is a C2 - not a 965 - so no hydraulic pump / pressure switch, right..?
Mine may well be a ground strap. Along with - or sometimes alone - I get a "blink" in the electrical system: The radio stops for a second (sometimes longer than a second, and I have to reset the code), and the radar detector resets...
I'm having the very same issue(s).... Mine is a C2 - not a 965 - so no hydraulic pump / pressure switch, right..?
Mine may well be a ground strap. Along with - or sometimes alone - I get a "blink" in the electrical system: The radio stops for a second (sometimes longer than a second, and I have to reset the code), and the radar detector resets...