No Shift/Harsh Shift/No Engagement, Transmission in Default, Check Transmission Warning Indicator Illuminated, Range Inhibited Indicator Illuminated, Transmission DTCs Set (Inspect/Repair TCM Harness)

Some customers/dealers may comment on any of the following conditions:

The cause of these conditions may be due to contamination of the transmission control module (TCM) connector and wiring that rubs on the TCM cover.

The TCM is mounted on the LH component box front panel and is located directly rearward of the front tire. This location places the TCM in the direct line of road splash, salt splash, snow and ice. This road debris could also cause damage to the front panel (1). Operation in this environment may allow moisture or water to enter the component box. If water, ice or debris enters the front panel of the component box, the TCM could be susceptible to malfunctioning and may cause any of the above conditions.

Use the following procedure to correct the above conditions.

1. Inspect the TCM (1) and the TCM wiring harness near the TCM cover for corrosion and/or damage. If necessary, replace the TCM.
2. Repair the TCM wiring harness. Refer to Wiring Repairs in the Wiring Systems sub-section of the Service Information.
3. Using a tie strap, secure the harness away from the TCM cover.

Rubber Extension (LH)





Rubber Extension (RH)




4. Attach a rubber extension such as a mudguard, or a portion of a mudguard (1) (obtained locally), between the front fender extension and the extension bracket. The rubber extension should extend approximately 381 mm (15 in) below the existing fender extension. The existing fasteners can be used to attach the extensions. Longer bolts may be required for attachment. Also add a 152 mm (6 in) rubber extension to close out the gap at the frame. These extensions should be added to the LH and RH sides of the vehicle.

The TCM can be obtained directly from Allison®.

For vehicles repaired under warranty, use: