What is it that i have to do to fix the problem and what does it mean? if i turn the heater fan control to settings 1-4 the blower does not come on at all, if i turn it to 5 it comes on intermittently along w/ the daytime running lights. the fuel gauge doesn't work properly either. it will stay reading "full" until i shift into park or nuetral, then it falls to "empty". the traction control is stuck in the off position and will not turn on. i have replaced the heater control module and the heater control resistor and reset the codes. the code pops right back up. p1635. i figure it to be a ground, but which ground and where is it located?
What engine ? 3.1 or 3.8 L
DTC P1635 5 Volt Reference Circuit , do you know what this is ?
The PCM uses the 5-volt Reference A circuit as a sensor feed to the following sensors:
• The TP sensor
• The MAP sensor
• The EGR valve pintle position sensor.
The PCM monitors the voltage on the 5-volt Reference A circuit. If the voltage is out of tolerance, DTC P1635 will set.
Diagnostic Aids
Important:: Be sure to inspect PCM and engine grounds for being secure and clean.
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
• Loose terminal connection
- Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
- Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
• Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
• Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
DTC P1635 - 5 Volt Reference A Circuit Step
Action
Values
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
YES - Go to Step 2
NO - Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission
2
Check the PCM and the engine grounds. Ensure that the grounds are clean and secure.
If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 11
NO - Go to Step 3
3
Turn OFF the ignition.
Disconnect the EGR.
Turn ON the ignition.
Use a DMM in order to measure the voltage between the 5-volt Reference A circuit and an engine ground.
Is the voltage near the specified value?
5 V
YES - Go to Step 5
NO - Go to Step 4
4
Is the voltage near the specified value?
0 V
YES - Go to Step 6
NO - Go to Step 8
5
Reconnect the EGR valve.
Disconnect the throttle position sensor.
Use a DMM in order to measure the voltage between the 5-volt Reference A circuit and an engine ground.
Is voltage near the specified value?
5 V
YES - Go to Step 10
NO - Go to Step 9
6
Monitor the DMM while disconnecting all other devices that are connected to the 5-volt Reference A one at a time.
If the voltage changes when one of the above components is disconnected, replace the component. Refer to the appropriate replacement procedure.
Did you replace a component?
--
YES - Go to Step 11
NO - Go to Step 7
7
Turn OFF the ignition.
Disconnect the PCM.
Check the 5-volt Reference A circuit for a short to ground.
If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 11
NO - Go to Step 10
8
Turn OFF the ignition.
Disconnect the PCM.
Turn ON the ignition.
Check the 5-volt Reference A circuit for a short to voltage.
If you find a problem, repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
YES - Go to Step 11
NO - Go to Step 10
9
Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .
Is the action complete?
--
YES - Go to Step 11
--
10
Important:: The replacement PCM must be programmed.
Replace PCM. Refer to Powertrain Control Module Replacement/Programming .
Is the action complete?
--
YES - Go to Step 11
--
11
Review and record the scan tool Failure Records data.
Clear the DTCs.
Operate the vehicle within the Failure Records conditions.
Use a scan tool in order to monitor the Specific DTC info for DTC P1635 until the DTC P1635 test runs.
Does the scan tool indicate that DTC P1635 failed this ignition?
--
Go to Step 2
System OK
PCM grounds at G113
G113
Lower left front of the engine, on the transaxle stud, near the starter
How to check the 5v reference circuit for short to ground Cadillac
SOURCE: Daytime running light/blower motor interaction
I have the same problem. I've heard the ignition switch harness is shorting out and replacing the ignition switch ($75-$125 part) will fix it. A few torx drivers and sockets are needed to replace it (a 4mm hex socket works for the column covers, but the bolts holding the ignition switch in are even smaller. I have it apart down to where I need a smaller torx socket to continue.)
SOURCE: Temperature sensor problem?
If you check in your power distribution box under hood, I believe relay # 2 is a rad fan relay, that could be a possible problem too. If other relays in the area are same number & 5 pins, or whatever yours is, you can try swapping them for testing it.
SOURCE: heater stays on hi havc won't turn off all fuses good
The resister is located under the dash in the passenger footwell area. It is to the driver's side of the blower motor up against the firewall.
To remove, it's easiest to remove the passenger seat to lay down on the car floor. Next, find the blower resistor, remove the connector, remove the one front bolt and just loosen the two bolts by the firewall. Pull the resistor down and out from the two bolts. Installation of the new resistor is the opposite of removal.
Hope this helps
SOURCE: Problems with 2001 grand am
The blower resistor is definitely your problem. They've been updated, it should be located in the blower housing, I believe way up under the dash on the passenger side.
If you have a cam sensor code, it is probably bad and needs to needs to be replaced. Sometimes a severely worn engine can cause this code to set. How many miles and which engine?
SOURCE: 2001 Pontiac Grand Prix GT multifunction switch problem?
I had the exact same problem, I changed the "ignition switch" because the contacts inside were burned, this is why you see all those troubles coming in and out at different moments. It costed me 150$ to do it myself, buy the switch on an online reseller, must cheaper than the dealer! Now everything is back to normal on my Grand Prix GT 99 exept that my headlights don't light up automatically when starting the car... I have to check my fuse/relay and switch to make sure everything is ok on that side.
Good luck.
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