For 1990-2009 cars
Engine Controls Components
Fuel Pump Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The Body Control Module (BCM) produces the Theft Deterrent Fuel Enable signal when ignition is ON and the proper key resistor pellet is sensed. The PCM monitors the Fuel Enable signal during crank. If the proper signal is present on the Theft Deterrent Fuel Enable circuit, the PCM enables fuel delivery and starter operation to allow the engine to start. If the PCM detects that the fuel enable signal is not present or incorrect while an attempt is made to start the engine, DTC P1629 will be set. The engine will not start and the starter motor will be disabled. This conditions will occur if the problem also affects inputs to the BCM. Refer to Vehicle Theft Deterrent System for further diagnosis.

### Conditions for Setting the DTC

• | DTC P1626 is not present.

• | An attempt is made to start the engine.

• | The PCM detects an incorrect signal on the Theft Deterrent Fuel Enable Circuit.

### Action Taken When the DTC Sets

• | The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

• | The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

### Conditions for Clearing the MIL/DTC

• | A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | DTC can be cleared by using the scan tool Clear Information function or by disconnecting the PCM battery feed.

### Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for:

• | Poor connection at PCM - Inspect harness connectors for the following items:

- | Backed out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal to wire connections

• | Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the vehicle theft deterrent module, turn the ignition ON and observe a DMM connected to the theft deterrent fuel enable circuit at the vehicle theft deterrent module harness connector while moving connectors and wiring harnesses related to the vehicle theft deterrent system. A change in voltage will indicate the location of the malfunction.

Review the Fail Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. 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.

#### DTC P1629 - Theft Deterrent Crank Signal Malfunction

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to the Powertrain On Board Diagnostic (OBD) System Check
2 | Important:: Before continuing diagnosis, ensure that the vehicle battery is fully charged. Attempt to start the engine. Does the engine crank? | -- | Go to Step 3 | Go to Vehicle Theft Deterrent (VTD) System Check .
3 |

1. Turn OFF the ignition switch.
2. Disconnect the body control module.
3. Turn ON the ignition switch.
4. Using a J 39200 DMM, measure voltage between the vehicle theft deterrent fuel enable circuit at the body control module harness connector and a known good ground.

Does voltage measure near the specified value?

5V

Go to Step 4

Go to Step 6

4 |

1. Turn OFF the ignition switch.
2. Reconnect the body control module.
3. Turn ON the ignition switch.
4. Backprobe the body control module connector to measure frequency between the vehicle theft deterrent fuel enable circuit and ground.

Is the frequency between the specified values?

40-60 Hz

Go to Step 5

Go to Step 8

5 |

1. Turn ON the ignition switch.
2. Clear DTC P1629.
3. Attempt to start the vehicle.

Does the vehicle start and continue running?

--

Go to Diagnostic Aids

Go to Step 7

6 |

1. Check the vehicle theft deterrent fuel enable circuit for an open, short to ground, or short to voltage.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 11

Go to Step 7

7 |

1. Check the theft deterrent fuel enable circuit for a poor connection at the PCM.
2. If a problem is found, replace faulty terminal. Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 11

Go to Step 9

8 |

1. Check for poor connections at the body control module.
2. If a problem is found, replace faulty terminal(s). Refer to Wiring Repairs .

Was a problem found?

--

Go to Step 11

Go to Step 10

9 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is action complete? | -- | Go to Step 11 | --
10 | Service the body control module. Is action complete? | -- | Go to Step 11 | --
11 |

1. Clear DTCs.
2. Observe VTD Fuel Disable on the scan tool while cranking the engine.

Does VTD Fuel Disable display Active?

--

Go to Step 2

System OK