Hey everyone,
I have a 95 Monte Carlo that belonged to my cousin who died in a four wheeling accident. Her brother, and I have been trying to get it going in memory of her so any, and all help will be most appreciated.
The problem with the car is that it is idling at around 1500 RPM's, and according to TunerPro the engine is requesting this speed. The only codes that I get is P1650 which indicates a malfunction in the #2 quad driver circuit. I looked this up on Alldata, and it states that this controls the EGR solenoids, and the TCC solenoids. I have unplugged the EGR with no difference in idle so I don't think the idle problem is associated with this code.
However, while running diagnostics with TunerPro, I noticed that the AC Clutch is always engaged according to TunerPro. I have disconnected the AC compressor plug, removed the relay, and both fuses, and have the cabin controls set to off, but the PCM still thinks the AC clutch is engaged.
So if the PCM is thinking that the clutch is engaged wouldn't it command a higher RPM to compensate for the load on the engine??
I have no real need for the AC right now, and we just want the car to run right in tribute to my cousin. So can I just cut the wires going to the PCM pertaining to the AC circuit? If so, does anyone know what wires this would be?
Also, according to Alldata P1650 should not trip the check engine light, which is on with no other codes being displayed. Could this be because the computer knows that the AC has not been requested, but the AC clutch is engaged?
I thank everyone in advance to their insight, and advice with this. I look forward to hearing your responses.
95 Monte Carlo AC Clutch Always Engaged
Moderators: robertisaar, dex
If the check engine light is on you could be in Limp Home Mode which usually raises idle.
A/C engaged on a properly running car will not raise the idle that high.
P1650 will i,uminate check engine light.
DTC P1650
CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) is used to control several components such as those illustrated above. The PCM controls these devices through the use of a Quad-Driver Module (QDM) . When the PCM is commanding a component "ON," the voltage potential of the output circuit will be "low" (near 0 volts). When the PCM is commanding the output circuit to a component "OFF," the voltage potential of the circuit will be "high" (near battery voltage). The primary function of the QDM is to supply the ground for the component being controlled.
Each QDM has a fault line which is monitored by the PCM. The fault line signal is available on the data stream for scan tool test equipment display on Tech 1. The PCM will compare the voltage at the QDM based on accepted values of the fault line. If the QDM B fault detection circuit senses a voltage other than the accepted value, the fault line will go from a "low" signal on the data stream to a "high" signal and Diagnostic Trouble Code P1650 will set.
DIAGNOSTIC TROUBLE CODE (DTC) P1650 WILL SET WHEN
The engine is running.
The PCM detects an improper voltage level on a circuit connected to QDM B.
The above conditions met for 5 seconds.
ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon) with a current DTC P1650 set. QDM B controls transmission shift solenoid A and B, Torque Converter Clutch (TCC) Pulse Width Modulated solenoid and three Exhaust Gas Recirculation (EGR) solenoids.
DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
If a QDM related DTC is stored, diagnose that DTC first. The repair made to the related DTC will repair DTC P1650 also.
This test will determine which QDM B control device has failed.
DIAGNOSTIC AIDS
Monitor the voltage at each terminal shown above while moving related harness connectors, including PCM harness. If the failure is induced, the voltage will change. This may help locate an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If DTC reoccurs with no apparent connector problem, replace PCM.
NOTICE:
PCM is protected by an internal circuit breaker.
PCM replacement is not necessary after repairing QDM B Quad driver controlled circuit or component
A/C engaged on a properly running car will not raise the idle that high.
P1650 will i,uminate check engine light.
DTC P1650
CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) is used to control several components such as those illustrated above. The PCM controls these devices through the use of a Quad-Driver Module (QDM) . When the PCM is commanding a component "ON," the voltage potential of the output circuit will be "low" (near 0 volts). When the PCM is commanding the output circuit to a component "OFF," the voltage potential of the circuit will be "high" (near battery voltage). The primary function of the QDM is to supply the ground for the component being controlled.
Each QDM has a fault line which is monitored by the PCM. The fault line signal is available on the data stream for scan tool test equipment display on Tech 1. The PCM will compare the voltage at the QDM based on accepted values of the fault line. If the QDM B fault detection circuit senses a voltage other than the accepted value, the fault line will go from a "low" signal on the data stream to a "high" signal and Diagnostic Trouble Code P1650 will set.
DIAGNOSTIC TROUBLE CODE (DTC) P1650 WILL SET WHEN
The engine is running.
The PCM detects an improper voltage level on a circuit connected to QDM B.
The above conditions met for 5 seconds.
ACTION TAKEN (PCM WILL DEFAULT TO)
The PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon) with a current DTC P1650 set. QDM B controls transmission shift solenoid A and B, Torque Converter Clutch (TCC) Pulse Width Modulated solenoid and three Exhaust Gas Recirculation (EGR) solenoids.
DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
If a QDM related DTC is stored, diagnose that DTC first. The repair made to the related DTC will repair DTC P1650 also.
This test will determine which QDM B control device has failed.
DIAGNOSTIC AIDS
Monitor the voltage at each terminal shown above while moving related harness connectors, including PCM harness. If the failure is induced, the voltage will change. This may help locate an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If DTC reoccurs with no apparent connector problem, replace PCM.
NOTICE:
PCM is protected by an internal circuit breaker.
PCM replacement is not necessary after repairing QDM B Quad driver controlled circuit or component
1990 Chevy Suburban
1994 Buick RoadMaSSter Estate Wagon LT1.
1972 IH 1210 Isky Cammed Balenced 345 TBI
GearHead-EFI.com EFI Conversions and Chip Tuners!
1994 Buick RoadMaSSter Estate Wagon LT1.
1972 IH 1210 Isky Cammed Balenced 345 TBI
GearHead-EFI.com EFI Conversions and Chip Tuners!