Info - VCM/PCM Replacement Due to Corrosion and/or Water Intrusion

This bulletin is being revised to update the service procedure for 1996-1999 vehicles and change warranty information. Please discard Corporate Bulletin Number 02-06-04-020A (Section 06 -- Engine/Propulsion System).

This bulletin is being issued to inform dealers that the VCM/PCM for the above listed vehicles may be susceptible to corrosion due to its mounting location under the hood near the left front fender. Any time the VCM/PCM is replaced due to corrosion, the engine wiring harness deflector should be replaced with a new redesigned deflector. This new deflector will more effectively channel windshield run-off water away from the VCM/PCM. Also, a road splash shield should be installed onto the VCM/PCM bracket to provide additional protection to the VCM/PCM. Use the appropriate procedure listed below.

For 1996-1999 Vehicles:

Install the new engine wiring harness deflector, P/N 15091839, road splash shield, P/N 15183966, and 2000 model year designed VCM/PCM bracket, P/N 15766026, since the road splash shield will not fit on the older design bracket.

1. Open the hood.
2. Remove the engine wiring harness deflector from the left front fender and discard.
3. Install the new engine wiring harness deflector. The new deflector attaches using only the front clip.
4. Remove the air cleaner assembly.
5. Disconnect the negative battery cable.
6. Remove the spring retainers off the edges of the VCM/PCM.
7. Slide the VCM/PCM out of the bracket.
8. Disconnect the VCM/PCM harness connectors.
9. Remove the nuts and the VCM/PCM mounting bracket.

Important: Before the new VCM/PCM bracket can be installed, the VCM/PCM fastening bail/latch must be relocated. Drill out casting dimples approximately 25 mm (1 in) above current holes using 4.76 mm (0.1875 in) drill bit and move bail/latch to new location.

10. Install the new 2000 model year designed VCM/PCM bracket, P/N 15766026, and nuts.
11. Install the new splash shield, P/N 15183966, as shown below. Ensure that the shield is properly snapped into position.
12. Connect the VCM/PCM harness connectors.
13. Insert the VCM/PCM into the bracket.
14. Install the retaining springs over the edges of the VCM/PCM.
15. Install the air cleaner assembly.
16. If a new VCM/PCM is being installed, program the VCM/PCM. Refer to VCM/PCM Reprogramming in the Engine Controls sub-section of the Service Manual.
17. Close the hood.

For 2000-2002 vehicles built prior to December 2001:

Install the new engine wiring harness deflector, P/N 15091839, road splash shield, P/N 15183966.

1. Open the hood.
2. Remove the engine wiring harness deflector from the left front fender and discard.
3. Install the new engine wiring harness deflector. The new deflector attaches using only the front clip.
4. Remove the air cleaner assembly.
5. Disconnect the negative battery cable.
6. Remove the spring retainers off the edges of the VCM/PCM.
7. Slide the VCM/PCM out of the bracket.
8. Disconnect the VCM/PCM harness connectors.
9. Remove the nuts and the VCM/PCM mounting bracket.
10. Install the new splash shield, P/N 15183966, as shown below. Ensure that the shield is properly snapped into position.
11. Connect the VCM/PCM harness connectors.
12. Insert the VCM/PCM into the bracket.
13. Install the retaining springs over the edges of the VCM/PCM.
14. Install the air cleaner assembly.
15. If a new VCM/PCM is being installed, program the VCM/PCM. Refer to VCM/PCM Reprogramming in the Engine Controls sub-section of the Service Manual.
16. Close the hood.

For 2002 vehicles built after December 2001:

Install the new engine wiring harness deflector, P/N 15091839, road splash shield, P/N 15183966. Vehicles were produced with the new deflector, however, manufacturing cut the deflector to aid in their assembly process. This modification may compromise the effectiveness of the deflector.

1. Open the hood.
2. Remove the engine wiring harness deflector from the left front fender and discard.
3. Install the new engine wiring harness deflector. The new deflector attaches using only the front clip.
4. Remove the air cleaner assembly.
5. Disconnect the negative battery cable.
6. Remove the spring retainers off the edges of the VCM/PCM.
7. Slide the VCM/PCM out of the bracket.
8. Disconnect the VCM/PCM harness connectors.
9. Remove the nuts and the VCM/PCM mounting bracket.
10. Install the new splash shield, P/N 15183966, as shown below. Ensure that the shield is properly snapped into position.
11. Connect the VCM/PCM harness connectors.
12. Insert the VCM/PCM into the bracket.
13. Install the retaining springs over the edges of the VCM/PCM.
14. Install the air cleaner assembly.
15. If a new VCM/PCM is being installed, program the VCM/PCM. Refer to VCM/PCM Reprogramming in the Engine Controls sub-section of the Service Manual.
16. Close the hood.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: