For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Tonneau Relay B+ | 1 | 1 | -- | --
Trunk Release Switch Signal | B2730 00 | 2 | 2 | --
Tonneau Latch Control | 1 | 1 | 1 | --
Trunk Relay Control | B3265 00 | B3265 00 | B3265 00 | --
Tonneau Latch Ground | -- | 1 | -- | --
Rear Closure Release Switch Ground | -- | 2 | -- | --
1. Tonneau Latch Malfunction 2. Rear Closure Release Switch Malfunction

### Circuit/System Description

The tonneau cover can be released by operating the rear closure release switch, the gear selector must be in Park for the tonneau cover latch to release.

The body control module (BCM) monitors the signal circuit to the rear closure release switch. When the rear closure release switch is pressed, the tonneau release signal is pulled low within the BCM. In response, the BCM applies ground to the tonneau relay control circuit, which energizes the coil side of the tonneau relay. The switch side of the tonneau relay then closes, supplying battery positive voltage through the relay and the control circuit to the tonneau latch. The tonneau latch, then releases the tonneau cover so that it may be manually raised to an open position.

### Reference Information

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Tonneau Cover Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the scan tool Trunk Switch parameter while pressing the rear closure release switch. The parameter should change between Active and Inactive.

⇒ | If the value does not change, refer to Rear Closure Release Switch Malfunction.

2. Command the Trunk Release Test with a scan tool, the tonneau latch should release the tonneau cover.

⇒ | If the tonneau latch does not release, refer to Tonneau Latch Malfunction.

### Circuit/System Testing

#### Rear Closure Release Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the rear closure release switch.
2. Test for less than 1 ohm between the ground circuit terminal listed below and ground:

• | RPO HSPO terminal 1

• | RPO HSV terminal B

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Trunk Switch parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.

• | RPO HSPO terminal 2

• | RPO HSV terminal A

4. Install a 3A fused jumper wire between the circuit terminals listed below. Verify the scan tool Trunk Switch parameter is Active.

• | RPO HSPO signal terminal 2 and ground terminal 1

• | RPO HSV signal terminal A and ground terminal B

⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the rear closure release switch.

#### Tonneau Latch Malfunction

1. Ignition OFF, disconnect the Tonneau Release relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.

⇒ | If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the Tonneau Release relay

4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

5. Ignition OFF, disconnect the harness connector at the tonneau latch.
6. Test for less than 1 ohm between the ground circuit terminal listed below and ground.

• | RPO HSPO terminal 1

• | RPO HSV terminal 4

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

7. Connect the harness connector at the tonneau latch.
8. Ignition ON, connect a 10A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the tonneau latch is activated.

⇒ | If the tonneau latch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the tonneau latch.

9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Trunk Release Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

11. If all circuits test normal, test or replace the Tonneau Release relay.

### Component Testing

#### Tonneau Latch Assembly

1. Ignition OFF, disconnect the harness connector at the tonneau latch.
2. Install a 10A fused jumper wire between the control terminal listed below and 12V.

• | RPO HSPO terminal 2

• | RPO HSV terminal 3

3. Install a jumper wire between the ground terminal listed below and ground. Verify the tonneau latch activates.

• | RPO HSPO terminal 1

• | RPO HSV terminal 4

⇒ | If the latch does not perform as specified, replace the tonneau latch.

#### Rear Closure Release Switch

1. Ignition OFF, disconnect the harness connector at the rear closure release switch.
2. Test for infinite resistance between the signal terminal and the ground terminals listed below with the switch in the open position.

• | RPO HSPO signal terminal 2 and ground terminal 1

• | RPO HSV signal terminal A and ground terminal B

⇒ | If not the specified value, replace the rear closure release switch.

3. Test for less than 2 ohms between the signal terminal and the ground terminals listed below with the switch in the closed position.

• | RPO HSPO signal terminal 2 and ground terminal 1

• | RPO HSV signal terminal A and ground terminal B

⇒ | If greater than the specified range, replace the rear closure release switch.

4. Test for infinite resistance between each terminal and the lid release switch housing/case.

⇒ | If not the specified value, replace the rear closure release switch.

#### Relay Test

1. Ignition OFF, disconnect the Tonneau Release relay.
2. Test for 65-90 ohms between terminals 85 and 86.

⇒ | If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If not the specified value, replace the relay.

4. Install a 10A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

⇒ | If greater than the specified range, replace the relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Control Module References for BCM replacement, setup and programming