HYDRA-MATIC 4L80-E Transmission Slipping/Flare On 1st or 2nd and/or 2nd to 3rd Upshift and No 3rd or 4th Gear Shudder During Initial Acceleration DTC P1870 Set
| Subject: | NPR EFI HYDRA-MATIC 4L80-E Transmission Slipping/Flare On 1st to 2nd to 3rd Upshift and No 3rd or 4th Gear Shudder During Initial Acceleration DTC P1870 Set. |
| Models: | 1996 NPR EFI models equipped with HDRA-MATIC 4L80-E automatic transmission. |
| Attention: | This Service Bulletin is intended for use by professional, qualified technicians. Attempting repairs or service without the appropriate training, tools, and equipment could cause injury to you or others and damage to your vehicle that may cause it not to operate properly. |
Service Information
Some affected vehicles may experience either transmission slipping or flare on the 1st to 2nd and/or 2nd to 3rd upshift, or no 3rd or 4th gear, or shudder during initial acceleration. DTC P1870 may also set.
The cause of this condition may be due to a poor internal ground between the two circuit boards in the vehicle control module (VCM). This poor internal ground may cause the VCM to command erratic line pressure at the pressure control solenoid.
To repair this condition, revise the VCM wiring harness using the Harness Jumper Wire Kit (Part No. 8-12167-310-0-) and the procedure described in this Service Bulletin.
Service Procedure
VCM Wiring Harness Removal
- Remove battery ground cable.
- Disconnect Connectors J1 (Blue), J2 (Attention), and J3 (Grey and Clear) from the VCM.
- Remove the wire from Connector J3 Pin 18 and relocate to Connector J1 and Pin 23.
VCM Wiring Harness Installation
- Install the jumper wire included in Harness Jumper Wire Kit (Part No. 8-12167-310-0) between Connector J2 Pin 26 and Connector J3 Pin 18.
- Install tag included in kit around wiring harness to denote harness has been modified.
- Reconnect Connectors J1, J2 and J3 to VCM.
- Connect battery ground cable.
When repairs have been completed, clear stored DTC P1870 using a scan tool; then check for proper transmission operation.
Important: If any of the following conditions are noted while checking the transmission
for proper operation, the transmission should be replaced:
• Transmission fluid oxidation or excessive sediment. • Transmission slipping or flare after this repair has been completed.
Parts Information
Part Number | Description | Qty |
|---|---|---|
8-12167-310-0 | Harness Jumper Wire Kit | 1 |
Warranty Information
Use the published Flat Rate Manual labor operation number N6112 for installation of the harness jumper wire kit.
If transmission replacement is required, use published labor operation number K7000.
Do not add the harness jumper kit to the transmission warranty claim. A separate warranty claim must be entered. Failure to enter the claim may cause claim payment delay.
