Test Description
WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step tests for a faulty tow/haul switch.
- 3: This step tests for voltage input from the BCM to the tow/haul switch.
- 6: This step tests for ground integrity.
Tow/Haul Switch/Indicator Always On or Inoperative
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| 1 |
|
- | Go to Intermittent Conditions in Engine Controls - 4.3L or Intermittent Conditions in Engine Controls - 4.8L, 5.3L and 6.0L | Go to Step 2 |
| 2 |
|
- | Go to Step 7 | Go to Step 3 |
| 3 | Using the DMM and the J 35616
, measure the voltage at the tow/haul switch signal circuit of the tow/haul switch connector. Is ignition voltage measured? |
- | Go to Step 6 | Go to Step 4 |
| 4 | Using the DMM and the J 35616
, measure the voltage at the tow/haul switch signal circuit of the body control module (BCM). Is ignition voltage measured? |
- | Go to Step 5 | Go to Step 8 |
| 5 | Test the signal circuit of the tow/haul switch for an open or shorted condition. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 9 | Go to Intermittent Conditions in Engine Controls - 4.3L or Intermittent Conditions in Engine Controls - 4.8L, 5.3L and 6.0L |
| 6 | Test the ground circuit of the tow/haul switch for an open or shorted condition. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 9 | Go to Intermittent Conditions in Engine Controls - 4.3L or Intermittent Conditions in Engine Controls - 4.8L, 5.3L and 6.0L |
| 7 | Replace the tow/haul switch. Refer to Shift Lever Replacement (With Tow/Haul Switch)Shift Lever Replacement (Without Tow/Haul Switch)
in Steering Wheel and Column. Did you complete the replacement? |
- | Go to Step 9 | - |
| 8 | Test the BCM for proper operation. Refer to Diagnostic Starting Point - Body Control System
in Body Control System. Did you find and correct the condition? |
- | Go to Step 9 | - |
| 9 | After the repair is complete, observe Tow/Haul Mode on the scan tool display, while cycling the tow/haul switch. Does the scan tool display Active when the switch is first pressed, and then Inactive when the switch is pressed again? |
- | System OK | Go to Step 1 |