Headlights again!
09-01-2014, 08:05 PM
#1
Veteran
Thread Starter
Headlights again!
Ok, if you didn't read this before I just purchased 97 C5. I like the pop up headlights, goes well with my 72 conv. I have rreplaced both nylon gears in the headlamp motors. Toke out the Duralast battery and put in an Optima yellow top. After reassembling the headlight and cleaning off the HL module in the passenger side the lights work sometimes and sometimes not. when pulling the stalk back to pass the brights come on but that is it. The headlamps come up extremely quiet when they do decide to come up. I cleared all the codes and went for a ride. Did the diagnostics and have one pcm P1571 H. all other codes remained clear. I am thinking it is either the ground for the light system or the stalk on the wheel. If it was the module I don't think they would work at all not just some of the time. Any ideas? I don't want to just blindly start replacing parts in hope that is it. I now apologize to my 72 vette for all the times I cussed at u for having slow headlights due to the cam producing lower vacuum. any experience / help would be appreciated!
09-01-2014, 09:48 PM
#2
Drifting
Member Since: Sep 2009
Location: cinnaminson n.j.
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St. Jude Donor '14
P1571
The PCM supplies 5.0 volts on the Desired Torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal this DTC sets.
CONDITIONS FOR SETTING THE DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
The desired torque signal is not received by the PCM for 3 seconds.
ACTION TAKEN WHEN THE DTC SETS
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The Malfunction Indicator Lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
The PCM battery voltage is interrupted.
Use a scan tool in order to clear the MIL/DTC.
DIAGNOSTIC AIDS
IMPORTANT: Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
The p1571 has nothing to do with the headlights, see above. I suggest you check all the fuses. If all are good, get a wiring diagram for the headlamps and actuators.
The PCM supplies 5.0 volts on the Desired Torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal this DTC sets.
CONDITIONS FOR SETTING THE DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
The desired torque signal is not received by the PCM for 3 seconds.
ACTION TAKEN WHEN THE DTC SETS
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The Malfunction Indicator Lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
The PCM battery voltage is interrupted.
Use a scan tool in order to clear the MIL/DTC.
DIAGNOSTIC AIDS
IMPORTANT: Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
The p1571 has nothing to do with the headlights, see above. I suggest you check all the fuses. If all are good, get a wiring diagram for the headlamps and actuators.
09-01-2014, 10:03 PM
#3
Veteran
Thread Starter
P1571
The PCM supplies 5.0 volts on the Desired Torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal this DTC sets.
CONDITIONS FOR SETTING THE DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
The desired torque signal is not received by the PCM for 3 seconds.
ACTION TAKEN WHEN THE DTC SETS
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The Malfunction Indicator Lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
The PCM battery voltage is interrupted.
Use a scan tool in order to clear the MIL/DTC.
DIAGNOSTIC AIDS
IMPORTANT: Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
The p1571 has nothing to do with the headlights, see above. I suggest you check all the fuses. If all are good, get a wiring diagram for the headlamps and actuators.
The PCM supplies 5.0 volts on the Desired Torque circuit to the Electronic Brake and Traction Control Module (EBTCM). The EBTCM toggles this 5.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction requested by the EBTCM. The EBTCM supplies this signal when it detects a wheel slip. In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Desired Torque signal failure. If the PCM does not receive the Desired torque signal this DTC sets.
CONDITIONS FOR SETTING THE DTC
The traction control has not failed.
The engine speed is greater than 500 RPM for 20 seconds.
The desired torque signal is not received by the PCM for 3 seconds.
ACTION TAKEN WHEN THE DTC SETS
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The Malfunction Indicator Lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
The PCM battery voltage is interrupted.
Use a scan tool in order to clear the MIL/DTC.
DIAGNOSTIC AIDS
IMPORTANT: Do not perform this diagnostic procedure if the customer's concern is not related to the ABS and/or the Traction Control system(s).
The following may cause an intermittent:
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
The p1571 has nothing to do with the headlights, see above. I suggest you check all the fuses. If all are good, get a wiring diagram for the headlamps and actuators.
Last edited by King Lear; 09-01-2014 at 10:35 PM.