Question about Pontiac Firebird
QDM stands for Quad Driver Module.The QDM is located inside the PCM (Powertrain Control Module),or the vehicle's computer.Think of a circuit breaker,like the electrical breaker box in your home.If a circuit,any circuit becomes overloaded,the breaker "clicks" and shuts off power to the circuit.It resets itself after the load is gone,or the key has been cycled.I have never seen an actual QDM go bad.To repair this problem,the coolant temp sensor will need to be checked for proper operation.This is done with a scan tool that can access data.If the PCM is seeing a proper reading from the temp sensor,then it's on to another area,possibly the fan relays.If the relay is bad,it can melt internally and either shut off voltage,or allow continuos voltage.Check the relays.The wiring to and from the fan is also another area to be checked,but check the simple stuff first.Other than those areas,PCM command would need to be monitored.Good luck.
Posted on Jul 18, 2008
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Posted on Jan 02, 2017
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Mar 31, 2017 | Cars & Trucks
MIL (SERVICE ENGINE SOON) telltale circuit
Upshift lamp circuit
Cooling fan relay circuit
A/C relay circuit
Fault detected for 5 seconds for DTC P1651. Fault detected for 20 seconds for DTC P1650.
Important: The QDM circuit is continuously checked when the engine is running.
May 18, 2015 | 1995 Saturn Sl
When the A/C is requested and the ambient temperature is more than 50?°C (122?°F).
A/C refrigerant pressure exceeds 1310 kPa (190 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?°C (284?°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans on under the following conditions:
Engine coolant temperature reaches 110?°C (230?°F).
A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTCs set.
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