1994 C2 ABS diagnostic failure
#1
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Hi guys.
I have a '94 C2 with ABS control unit part number 99361812500. The ABS warning light comes on from time to time, and I cannot find the reason.
It is not possible to contact this unit with any Porsche OBD diag tool. Does this early 993 have the same limitation as the 964 C2's, no on-board diagnostic possibilities? This ABS control unit is different from the 964 C2.
All tips welcome.
Cheers,
Tore
I have a '94 C2 with ABS control unit part number 99361812500. The ABS warning light comes on from time to time, and I cannot find the reason.
It is not possible to contact this unit with any Porsche OBD diag tool. Does this early 993 have the same limitation as the 964 C2's, no on-board diagnostic possibilities? This ABS control unit is different from the 964 C2.
All tips welcome.
Cheers,
Tore
#3
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Adding to what Patrik said, does this only occur when the car is moving?
As to a 1994 having ABS on board diagnostics, I have seen posts in other places indicating yes, here's one:
http://www.911uk.com/viewtopic.php?p=483929
Have you tried using a Hammer or similar?
As to a 1994 having ABS on board diagnostics, I have seen posts in other places indicating yes, here's one:
http://www.911uk.com/viewtopic.php?p=483929
Have you tried using a Hammer or similar?
#4
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It will come on from time to time during driving when the system senses wheel slip. You can also feel it in the brake peddle when it is actuated.
Durametric can run the ABS OBD Codes and can tell you which sensor has a problem.
I suspect in most cases just cleaning the 4 sensors' plugs on each strut will solve most sensor issues, unless a rotor or hub was recently disturbed altering the sensors' proximity to it's reading ring.
My experience was with the ABS relay(s) in the trunk. I had problems with the system only once and replaced the two inexpensive relays in the frrunk and resolved the issue.
Durametric can run the ABS OBD Codes and can tell you which sensor has a problem.
I suspect in most cases just cleaning the 4 sensors' plugs on each strut will solve most sensor issues, unless a rotor or hub was recently disturbed altering the sensors' proximity to it's reading ring.
My experience was with the ABS relay(s) in the trunk. I had problems with the system only once and replaced the two inexpensive relays in the frrunk and resolved the issue.
#5
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Hi guys.
I have a '94 C2 with ABS control unit part number 99361812500. The ABS warning light comes on from time to time, and I cannot find the reason.
It is not possible to contact this unit with any Porsche OBD diag tool. Does this early 993 have the same limitation as the 964 C2's, no on-board diagnostic possibilities? This ABS control unit is different from the 964 C2.
All tips welcome.
Cheers,
Tore
I have a '94 C2 with ABS control unit part number 99361812500. The ABS warning light comes on from time to time, and I cannot find the reason.
It is not possible to contact this unit with any Porsche OBD diag tool. Does this early 993 have the same limitation as the 964 C2's, no on-board diagnostic possibilities? This ABS control unit is different from the 964 C2.
All tips welcome.
Cheers,
Tore
I'm pretty sure the Bosch Hammer that you sell will do the trick, if you have an OBD1 port.
Please advise, if the Bosch Hammer does not...
Thx in advance.
Last edited by nine9six; 04-24-2018 at 10:54 PM.
#6
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Thanks guys.
As mentioned in my initial post, there is no OBD connection to the ABS control unit using Scantool, Porsche hammer, PST-2 or PIWIS.
The ABS lamp sometimes comes on at start, sometimes when driving.
I dont' like to change parts or do other actions without proper diagnosis. Since yesterday, I have dug up the '94 (and '95/1) schematics, and see that the ABS unit in question does indeed have a OBD connection. (K and L wires) I'll start fault finding on these wires to the unit to see if I get a Porsche diag tool connection.
Cheers,
Tore
As mentioned in my initial post, there is no OBD connection to the ABS control unit using Scantool, Porsche hammer, PST-2 or PIWIS.
The ABS lamp sometimes comes on at start, sometimes when driving.
I dont' like to change parts or do other actions without proper diagnosis. Since yesterday, I have dug up the '94 (and '95/1) schematics, and see that the ABS unit in question does indeed have a OBD connection. (K and L wires) I'll start fault finding on these wires to the unit to see if I get a Porsche diag tool connection.
Cheers,
Tore
#7
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I've been having exactly the same problem on my car also a '94 model.It happens more often when it's raining. Ign. off, restart and it does not happen again for a while. I will follow this thread with interest. I suspect a corroded electrical contact somewhere in the system but these intermittant electrical problems are a real pain to find.
I had an occasional misfire on my 944 everytime I took it into the shop it was working fine, on a hunch I replaced the crank sensor et voila.
But as you say you can spend a lot of money with trial and error, Tore.
I had an occasional misfire on my 944 everytime I took it into the shop it was working fine, on a hunch I replaced the crank sensor et voila.
But as you say you can spend a lot of money with trial and error, Tore.
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#8
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Endoman, thanks.
I have tried most of the intermittent contact suspects, ABS control unit connector, both ABS relays and the instrument clock connector. All have been inspected and reseated several times. What irritates me that the cause might be stored as a fault code in the control unit, but there's no diag contact. Yet.
Cheers,
Tore
I have tried most of the intermittent contact suspects, ABS control unit connector, both ABS relays and the instrument clock connector. All have been inspected and reseated several times. What irritates me that the cause might be stored as a fault code in the control unit, but there's no diag contact. Yet.
Cheers,
Tore