GM Service Manual Online
For 1990-2009 cars only

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.

DTC Descriptor

DTC B3667: Tonneau Release Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+ - Folding Top Control Module

1

1

--

--

B+ - Tonneau Release Relay

2, 3, 5

2, 3, 4, 5

--

--

Folding Top Cover Latch Actuator Control

2, 5

2, 3, 4, 5

5, 6

--

Folding Top Cover Release Relay Control

B3667

B3667

B3667, 6

--

Ground - Folding Top Cover Latch Actuator

--

2, 3, 5

--

--

Ground - Folding Top Control Module

--

1

--

--

Ground - Tonneau Release Relay

--

B3667

--

--

1. No communication with the FTC module.

2. Power folding top is inoperative

3. Power folding top does not open or complete the top opening procedure.

4. Power folding top does not close or complete the top closing procedure.

5. Folding top stowage compartment lid release inoperative

6. DIC Warning Message

Circuit/System Description

When the power folding top is operated to open or close the folding top, the body control module (BCM) controls the folding top cover latch release operation through the folding top cover release relay control circuit and the tonneau release relay. The relay energizes and applies battery positive voltage to the folding top cover latch actuator. The circuit that generated this diagnostic trouble code (DTC) is the folding top cover release relay control circuit that is wired between the BCM and the tonneau release relay. The BCM applies a 12 volt low current voltage to this circuit to monitor the integrity of this circuit.

Conditions for Running the DTC

    • The FTC module must be powered and can not have B1327 or B1328 set as active DTCs for this DTC to set.
    • The BCM monitors the voltage of this circuit at all times even when the ignition is in the Off position.
    • The module voltage must be 9-16 volts.

Conditions for Setting the DTC

    • Open detected in the relay control circuit.
    • Short to battery voltage detected in the relay control circuit.
    • Short to ground detected in the relay control circuit.
    • Open in the ground circuit of the tonneau release relay.

Action Taken When the DTC Sets

    • Current and history DTCs are stored.
    • Power folding top operation is disabled until the ignition is cycled OFF/Run ACC.

Conditions for Clearing the DTC

    • This DTC will clear on the current status after the condition for setting the fault is corrected.
    • A history DTC will clear after 50 consecutive ignition cycles without a fault present.

Diagnostic Aids

    • When using the scan tool, the folding top cover is referenced as the tonneau.
    • Removing the tonneau release relay will set a DTC and stop power folding top operation. Once the relay is replaced, the ignition must be cycled OFF then Run ACCY in order to continue operation.
    • Whenever the open/close control switch is released or the top becomes inoperative in a suspended state, pressure will be maintained in the hydraulic system to avoid drifting and damage of components. After 4 minutes, the FTC module will gradually release the hydraulic pressure allowing the top to gradually settle to a resting position.

Reference Information

Schematic Reference

Folding Top Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Folding Top 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

When either the top open or top close control switch is pressed, the folding top cover should unlatch and rise to the open position. The scan tool Tonneau Latch Switch parameter should be Ajar.

Circuit/System Testing

  1. Ignition OFF, disconnect the tonneau release relay.
  2. Test for less than 5 ohms between the ground circuit terminal 86 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the control circuit terminal 85 and ground.
  5. Cycle the ignition OFF and ON in order to reset the BCM.
  6. Ignition ON, command the Tonneau Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
  7. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  8. If all circuits test normal, test or replace the tonneau release relay.

Component Testing

Tonneau Release Relay

  1. Ignition OFF, disconnect the tonneau release relay.
  2. Test for 60-120 ohms between terminals 85 and 86.
  3. If the resistance is not within the specified range, replace the relay.
  4. Test for infinite resistance between the following terminals:
  5. • 30 and 85
    • 30 and 86
    • 30 and 87
    If not the specified value, replace the relay.
  6. Install a 3A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.
  7. 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 FTC module and BCM replacement, setup, and programming