DTC P0656 Fuel Level Output Circuit. Pontiac Grand Prix 1999

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.1L 🢒 DTC P0656 Fuel Level Output Circuit

Cell 20: Power, Ground, MIL, and DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

Output Driver Modules (ODMs) are used by the PCM to turn on many of the current-driven devices that are needed to control various engine and Transaxle functions. ODMs have the capability of diagnosing each output circuit individually. DTC P0656 set indicates an improper voltage level on the output circuit that controls the fuel gauge.

Conditions for Running the DTC

The ignition is on.

Conditions for Setting the DTC

•	An improper voltage level has been detected on the output circuit which controls the fuel gauge.

•	The above conditions are present for at least 30 seconds.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The history DTC clears after 40 malfunction free warm-up cycles.

•	The PCM receives a clear code command from the scan tool.

Diagnostic Aids

Check for the following conditions:

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.

•	Poor terminal connection.

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems.

•	Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

•	Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

Test Description

Number(s) below refer to the step number(s) on the diagnostic table:

Normally, ignition feed voltage should be present on the output control circuit with the PCM disconnected and the ignition turned on.

Checks for a shorted component or a short to B+ on the output control circuit. Either condition would result in a measured current of over 1.5 amps. Also checks for a component that is going open while being operated, resulting in a measured current of 0 amps.

Checks for a malfunctioning instrument cluster.

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed..

Step	Action	Value(s)	Yes	No
1	Was the Powertrain OBD System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Was the Instrument Cluster System check preformed?	--	Go to Step 3	Go to Instrument Cluster System Check
3	Turn OFF the ignition switch. Disconnect the PCM. Turn on the ignition switch. Using a J 39200 DMM, measure voltage between the fuel level output circuit at the PCM harness connector and ground. Is the voltage near the specified value?	B+	Go to Step 4	Go to Step 7
4	Set the J 39200 DMM to the 10 amp scale and install the J 39200 DMM to measure current between the affected PCM output circuit and ground. Monitor the current reading on the J 39200 DMM for at least 2 minutes. Does the current reading remain between the specified values?	0.05-1.5 Amps	Go to Step 12	Go to Step 5
5	Disconnect the instrument panel cluster. Leave the PCM disconnected Measure voltage between the fuel level output circuit and ground. Is the voltage at the specified value?	0.0V	Go to Step 15	Go to Step 6
6	Locate and repair the short to voltage in the affected PCM output circuit. Refer to Wiring Repairs . Is the action complete?	--	Go to Step 17	--
7	Check the ignition feed fuse for the instrument panel cluster. Is the fuse blown?	--	Go to Step 8	Go to Step 9
8	Locate and repair the short to ground in the ignition feed circuit for the instrument panel cluster. Refer to Wiring Repairs . Replace the fuse. Is the action complete?	--	Go to Step 17	--
9	Disconnect the instrument panel cluster. Refer to Instrument Cluster Replacement . Turn on the ignition switch. Measure voltage between the ignition feed circuit for the instrument panel cluster and ground. Is the voltage near the specified value?	B+	Go to Step 10	Go to Step 14
10	Check the fuel level control circuit for an open or a short to ground. If a problem is found repair as necessary. Refer to Wiring Repairs . Was a problem found?	--	Go to Step 17	Go to Step 11
11	Check the fuel level control circuit and the ignition feed circuit for a poor connection at the instrument panel cluster. If a problem is found, replace the terminal(s). Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs . Was a problem found?	--	Go to Step 17	Go to Step 15
12	Turn OFF the ignition switch. Leave the PCM disconnected Turn the ignition switch on. Connect one end of a fused jumper to the fuel level output circuit and touch the other end to ground for at least 30 seconds. Does the fuel gauge indicate EMPTY?	--	Go to Step 13	Go to Diagnostic Aids
13	Check the fuel level output control circuit for a poor connection at the PCM. If a problem is found, replace the terminal. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs . Was a problem found?	--	Go to Step 17	Go to Step 16
14	Locate and repair open in the ignition feed circuit to the instrument panel cluster indicator lamps. Refer to Wiring Repairs . Is the action complete?	--	Go to Step 17	--
15	Replace the instrument panel cluster. Refer to Instrument Cluster Replacement . Is the action complete?	--	Go to Step 17	--
16	Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete?	--	Go to Step 17	--
17	Operate the affected lamp using the scan tool output tests function. Does the affected lamp operate properly?	--	System OK	Go to Step 3