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.

Circuit/System Description

The folding top control (FTC) module receives battery positive voltage on terminal 26 from the FOLDING TOP MAIN POWER fuse. The FTC module also receives battery positive voltage on terminal 24 from the FOLDING TOP LOGIC POWER fuse. Ground is provided to the FTC module through terminal 25 and terminal 27 from G301. The FTC module communicates on the low speed GMLAN serial data circuit using terminal 1 and terminal 2. When Open is selected on the folding top open/close switch, the retractable roof open signal circuit terminal 22 of the FTC module is pulled low. When Close is selected on the folding top open/close switch, the retractable roof close signal circuit terminal 10 of the FTC module is pulled low. It the conditions are correct for folding top operation, the FTC module will command the folding top in the requested direction.

Diagnostic Aids

Before any movement of the top is allowed, the FTC module must be aware of the following conditions:

    • The ignition must be in RUN.
    • The transmission must be in PARK.
    • The pump motor temperature and the outside temperature must be within operating range.
    • The decklid, also referred to as a rear compartment lid or a trunk, must be closed.
    • The cargo cover, also referred to as a luggage barrier or partition panel, must be installed, prior to opening top.

Reference Information

Schematic Reference

Folding Top Schematics

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

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

  1. Ignition ON, observe the scan tool Luggage Barrier in Place parameter. The reading should be Yes.
  2. If the parameter is No, perform the Luggage Barrier Inoperative test.
  3. Perform the Folding Top Inoperative from the Open/Close Switch test.

Circuit/System Testing

Luggage Barrier Inoperative

  1. Ignition OFF, disconnect the rear compartment partition position switch (S20).
  2. 2. Test for less than 3 ohms of resistance between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Luggage Barrier In Place parameter is Yes.
  5. If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the FTC module.
  6. If all circuits test normal, test or replace the rear compartment partition position switch.

Folding Top Inoperative from the Open/Close Switch

  1. Ignition OFF, disconnect the folding top open/close switch.
  2. Test for less than 2 ohms of resistance between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Top Control Switch parameter is Idle.
  5. If the parameter is Opening, test the signal circuit terminal C for a short to ground.
    If the parameter is Closing, test the signal circuit terminal A for a short to ground.
  6. Install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool Top Control Switch parameter is Opening.
  7. If the parameter is Idle, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the FTC module.
  8. Install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Top Control Switch parameter is Closing.
  9. If the parameter is Idle, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the FTC module.
  10. If all circuits test normal, test or replace the folding top open/close switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Folding Top Control Module Replacement
    •  Convertible Top Switch Replacement
    •  Rear Compartment Side Trim Replacement - Right Side