DTC P1626 Theft Deterrent Fuel Enable Signal Lost

Circuit Description

The Vehicle Theft Deterrent system consists of the following components:

• Powertrain Control Module (PCM)
• Body Control Module (BCM)
• Ignition Lock and Key

The Vehicle Theft Deterrent system is designed to disable vehicle operation if the incorrect key or starting procedure is used. The Body Control Module enables the crank circuit to the starter and sends a signal to the PCM if the correct key is being used. If the proper signal does not reach the PCM on the fuel enable circuit, the PCM will not pulse the injectors ON and thus not allow the vehicle to continue to operate, even if the crank circuit is bypassed. The proper signal is between 40-60 Hz and is measured using the DC scale on the DMM.

Conditions for Running the DTC

The Engine is running or cranking.

Conditions for Setting the DTC

• The PCM does not receive the correct signal from the Body Control Module.
• The condition is present for less than 1.0 second.

Action Taken When the DTC Sets

• The PCM stores the DTC information into memory when the diagnostic runs and fails.
• The Malfunction Indicator Lamp (MIL) will not illuminate.
• The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
• The engine starts and then stalls or the starter does not engage.

Conditions for Clearing the DTC

• A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
• A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
• Use a scan tool in order to clear the DTC.

Diagnostic Aids

• Inspect the GAGE fuse for an open. The GAGE fuse open casues DTC P1626 to set. Refer to Wiring Repairs In Wiring Systems.
• If the engine starts and then stalls, the Body Control Module is not suppling the appropriate signal or the theft deterrent fuel enable circuit is open, shorted to a ground, or shorted to a voltage.
• Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the freeze frame and/or failure records data can help determine how many miles since the DTC set. The Fail counter and the Pass counter can also aid in determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that the PCM recorded. This will isolate when the DTC failed.
• For an intermittent condition, refer to Symptoms .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2. An engine that does not crank and a DTC P1626 is set, indicates that there is a theft deterrent system condition. An incorrect ignition key or an incorrect starting procedure causes a no crank condition.

For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents damage to the harness connector terminals.

3. An engine that does not crank indicates there is a condition with the Body Control Module.

4. This step determines if the Powertrain Control Module is capable of sending a 5.0 volt signal to the BCM.

5. This step determines if the Body Control Module is capable of sending a signal to the PCM. The Body Control Module sends the PCM a 40-60 Hz signal.

6. This step determines if the condition is intermittent. If the engine starts and continues to operate, you may have corrected the condition during diagnoses. Inspect all connections at the BCM and the PCM.

Step	Action	Value(s)	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to A Powertrain On Board Diagnostic (OBD) System Check
2	Turn ON the ignition leaving the engine OFF. Use the scan tool to clear the DTCs. Select the Diagnostic Trouble Code (DTC) option and the specific DTC option, then enter the DTC number using the scan tool. Does the scan tool indicate that this diagnostic failed this ignition?	--	Go to Step 3	Go to Diagnostic Aids
3	Does the engine crank?	--	Go to Step 4	Go to Vehicle Theft Deterrent (VTD) System Check in Theft Deterrent
4	Turn OFF the ignition. Disconnect the BCM connector. Refer to Body Control Module Replacement in Body Control System. Turn ON the ignition leaving the engine OFF. Measure the voltage at the fuel enable circuit at the BCM harness connector using the DMM J 39200 . Is the voltage near the specified voltage?	5.0 Volts	Go to Step 5	Go to Step 7
5	Turn OFF the Ignition. Reconnect the BCM. Turn ON the Ignition leaving the engine OFF. Select the DC volts and the Hertz (Hz) scale using the DMM J 39200 . Backprobe one lead of the DMM J 39200 to the theft deterrent fuel enable circuit at the BCM harness connector and the other lead to ground using the DMM J 39200 . Is the hertz signal within the specified range?	40-60Hz	Go to Step 6	Go to Step 8
6	Capture Info using the scan tool. Clear the DTCs. Attempt to start the engine. Does the engine start and continue to operate?	--	Go to Diagnostic Aids	Go to Step 9
7	Test the theft deterrent fuel enable circuit for the following: An open A short to ground A short to B+ If you find a circuit condition repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 9
8	Inspect the terminal tension for the fuel enable circuit at the BCM harness connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. If you find a poor connection, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 11
9	Inspect the terminal tension for the fuel enable circuit at the PCM harness connector. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. If you find a poor connection, repair the terminal as necessary. Refer to Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 10
10	Important Program the replacement PCM. Refer to PCM Replacement/Programming . Replace the PCM. Is the action complete?	--	Go to Step 12	--
11	Replace the Body Control Module. Refer to Body Control Module Replacement in Body Control Systems. Is the action complete?	--	Go to Step 12	--
12	Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool. Idle the engine at the normal operating temperature. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable. Does the scan tool indicate that this test ran and passed?	--	Go to Step 13	Go to Step 2
13	Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed?	--	Go to the applicable DTC table	System OK