ACD Malfunction: Code 74
ACD Malfunction: Code 74
I was at the track last month in hot weather and on the second day my ACD lights all went on. After restarting the car for the next session they were normal again but only for a few minutes.
Eventually they got to the point of the lights always being on and giving me a code 74 when I check them, which is supposed to be for the proportional valve and wiring.
Originally the car would prime the pump with the key turned and throttle pressed but now it doesn't even attempt it and the relay doesn't click, does the ACD computer not prime the pump if there is an existing error? I unplugged the battery for a while but it didn't help.
Pump and proportioning valve solenoid both work fine with 12v applied. The internals of the pump are pristine, I bought this unit used a couple of years ago but it must have been a factory replacement or something. I checked the pump wiring and it was good, as well as the relay and fuses.
At this point the only possibilities I can come up with is the computer itself malfunctioning or the proportioning valve itself somehow even though it opens fine. Has anyone experienced a code 74? Any ideas of what might be going on?
And for the record driving on track with an open center differential is a pain.
Eventually they got to the point of the lights always being on and giving me a code 74 when I check them, which is supposed to be for the proportional valve and wiring.
Originally the car would prime the pump with the key turned and throttle pressed but now it doesn't even attempt it and the relay doesn't click, does the ACD computer not prime the pump if there is an existing error? I unplugged the battery for a while but it didn't help.
Pump and proportioning valve solenoid both work fine with 12v applied. The internals of the pump are pristine, I bought this unit used a couple of years ago but it must have been a factory replacement or something. I checked the pump wiring and it was good, as well as the relay and fuses.
At this point the only possibilities I can come up with is the computer itself malfunctioning or the proportioning valve itself somehow even though it opens fine. Has anyone experienced a code 74? Any ideas of what might be going on?
And for the record driving on track with an open center differential is a pain.
I was at the track last month in hot weather and on the second day my ACD lights all went on. After restarting the car for the next session they were normal again but only for a few minutes.
Eventually they got to the point of the lights always being on and giving me a code 74 when I check them, which is supposed to be for the proportional valve and wiring.
Originally the car would prime the pump with the key turned and throttle pressed but now it doesn't even attempt it and the relay doesn't click, does the ACD computer not prime the pump if there is an existing error? I unplugged the battery for a while but it didn't help.
Pump and proportioning valve solenoid both work fine with 12v applied. The internals of the pump are pristine, I bought this unit used a couple of years ago but it must have been a factory replacement or something. I checked the pump wiring and it was good, as well as the relay and fuses.
At this point the only possibilities I can come up with is the computer itself malfunctioning or the proportioning valve itself somehow even though it opens fine. Has anyone experienced a code 74? Any ideas of what might be going on?
And for the record driving on track with an open center differential is a pain.
Eventually they got to the point of the lights always being on and giving me a code 74 when I check them, which is supposed to be for the proportional valve and wiring.
Originally the car would prime the pump with the key turned and throttle pressed but now it doesn't even attempt it and the relay doesn't click, does the ACD computer not prime the pump if there is an existing error? I unplugged the battery for a while but it didn't help.
Pump and proportioning valve solenoid both work fine with 12v applied. The internals of the pump are pristine, I bought this unit used a couple of years ago but it must have been a factory replacement or something. I checked the pump wiring and it was good, as well as the relay and fuses.
At this point the only possibilities I can come up with is the computer itself malfunctioning or the proportioning valve itself somehow even though it opens fine. Has anyone experienced a code 74? Any ideas of what might be going on?
And for the record driving on track with an open center differential is a pain.
This could be useful if you find the solenoid is the problem.
Last edited by CDrinkH2O; Jun 11, 2021 at 10:40 AM. Reason: added YT vid
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