P1639 Cadillac PCM 5 Volt Reference Voltage Circuit Condition
Possible causes
– Sensor using 5 volt reference line shorted to ground
– Circuit short to ground
– Circuit short to ground
What about the obd code?
If the voltage is out of tolerance, the PCM will set DTC P1639 Cadillac.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P1639 Cadillac Description
The powertrain control module (PCM) uses the 5-volt reference 2 circuit as a sensor feed for the A/C refrigerant pressure sensor. The PCM monitors the voltage on the 5-volt reference 2 circuit.
Cadillac Vehicle:Cadillac CTS Coupe, Cadillac CTS-V Coupe , Cadillac Eldorado , Cadillac Escalade EXT , Cadillac ATS , Cadillac CTS , Cadillac CTS Sedan , Cadillac CTS Sport Sedan , Cadillac CTS-V , Cadillac CTS-V Sedan , Cadillac Catera , Cadillac DTS , Cadillac DeVille , Cadillac STS-V , Cadillac STS , Cadillac Seville , Cadillac XTS , Cadillac XLR , Cadillac XLR Platinum , Cadillac Escalade , Cadillac SRX