DTC 41

Code 41 - No Distributor Reference Signal:

Wiring Diagram for Code 41 - No Distributor Reference Signal:

CODE 41 - NO DISTRIBUTOR REFERENCE SIGNAL


Circuit Description:

Code 41 says that there are no distributor references pulses to the ECM at a specified engine vacuum. This code could set with the key "ON", engine "Not Running" if the VAC sensor was defective by indicating "Engine Running" voltage with just the key "ON". With a constant open or ground in the reference signal circuit, Code 12 would be set along with a 41. Use Chart 12 if 12 and 41 are set. Code 41 alone indicates the problem is intermittent. When the distributor reference line signal is lost, the engine runs full rich and with retarded (base) spark timing. The result is poor performance, poor fuel economy, and possibly rotten egg odor from exhaust.


Test Description:

1. Checks to see if VAC sensor voltage changes with loss of vacuum supply. A good sensor will change voltage at Terms. "A" to "B" by 1 volt or more.

1A. Since the voltage change was less than 1 volt, the problem is in the Vacuum system. The ECM has "seen" engine running vacuum equivalent with no distributor reference signal, with the key "ON", engine not running.


2. Checks for cause of an intermittent open or ground in the distributor circuit. Fault could also be an intermittent stuck Vacuum sensor that has the same voltage output as an engine "running" with only the key "ON", thus, no reference signal. Terminals must be removed from connectors to properly check them. The distributor pick-up coil should also be checked.