A/T - No Upshift After Cold Start, Intermittent DTC 87

File In Section: 7 - Transmission

Bulletin No.: 67-71-53A

Date: June, 1997

Subject:
No Upshift/2nd Gear Only After Cold Start-Intermittent DTC 87 - High Ratio Error (Replace EPROM)

Models:
1994-95 Chevrolet and GMC C, K, P Truck, G Van
1996 Chevrolet and GMC P Truck, G Van
equipped with HYDRA-MATIC 4L80E Automatic Transmission (RPO MT1)

This bulletin is being revised to add Part Numbers for Gasoline/Diesel engines that are TCM controlled parts and to include all Engine applications. Please discard Corporate Bulletin Number 67-71-53 (Section 7 - Transmission).

Condition

Some owners may comment about no transmission upshift after a cold start. In conjunction, Diagnostic Trouble Code (DTC) 87 is setting intermittently causing the PCM to command the default action of second gear only.

Cause

The commanded shift to third gear or fourth gear has taken longer than 2 seconds with a minimum 25% TP Sensor reading which has caused DTC 87 to set.

Correction

If normal diagnostics fail to lead to a resolution or the condition cannot be duplicated, replace the EPROM.

Service Information/Procedure

















Check the PCM for a current or history DTC 87. If DTC 87 is present, refer to the appropriate Service Manual for diagnosis of DTC 87. Refer to corporate bulletin # 577115 for additional information on diagnosing DTC 87. If the diagnosis fails to lead to a resolution and DTC 87 only sets after a cold start, replace the EPROM. Refer to the appropriate Service Manual for EPROM replacement. It is a good idea to verify the new EPROM I.D. with a scan tool against the application listed below.

The service EPROM raises the DTC 87 shift time parameter to 4 seconds and the code enabling temperature to 20°C (68°F).

Parts Information

Important:
In 1994, the L65 and L56 engines changed fuel injection pumps that required a new EPROM. The current fuel injection pump will service prior models. Be sure to match the EPROM with the proper engine fuel injection pump.

Parts are currently available through GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation Labor Time

J6364 Use published labor
operation time.