Engine Controls - Revised Code 26 & Chart C-8D
89Pontiac12Bulletin Number: 89-6-49
Reference Number: 916516
Publish Date: 6/89
SERVICE MANUAL UPDATE - SECTION
Subject: 6E3 - DRIVEABILITY AND EMISSIONS REVISED CODE 26/ADD CHART C-8D 2.3L (VIN D)
Models
Affected: 1988-89 GRAND AM
This bulletin serves to update Code 26 (Page 2 of 3) Facing Page "Diagnostic Aids" and to add Chart C-8D Facing Page and Chart in Section 6E3 "Driveability And Emissions" of the 1988 and 1989 Service Manuals with 2.3L Grand Am (VIN D) applications.
CODE 26
(Page 2 of 3)
QUAD-DRIVER (QDM) CIRCUIT 2.3L (VIN D) "N" SERIES (PORT)
Diagnostic Aids:
Intermittent open or ground in controlled circuit will cause Code 26 if present continuously for 20 seconds or longer. Intermittent Code 26 may be caused by an improperly functioning second or third gear switch. Refer to CHART C-8D for proper gear switch operation.
CHART C-8D
TRANSMISSION GEAR SWITCHES CIRCUIT CHECK 2.3L (VIN D) "N" SERIES (PORT)
Circuit Description:
CHART C-8D is used to check the 2nd and 3rd gear switch inputs to the ECM. Transmission gear input signals to the ECM are determined as follows:
1st gear = 2nd gear switch closed
(also P/N & R) 3rd gear switch open
2nd gear = 2nd gear switch open
3rd gear switch open
3rd gear = 2nd gear switch open
3rd gear switch closed
CHART C-8D:
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. Step one checks for an open or grounded circuit between transmission connector and ECM. Since the ECM terminals are normally high, B+ should be indicated at both terminals with the connector removed. A DVM must be used for this step.
2. A test light to B+ is used in this step to check transmission switches for the normal state. This is 1st gear (or P/N) state. The light should be "ON" for the N.C. 2nd gear switch. Use of the wiring probe kit J 35616 will assist in this and step 3.
3. The third step checks to see if the transmission switches function normally. In third gear both switches should have changed from their original 1st gear state.
Diagnostic Aids:
A sticky or improperly functioning 2nd or 3rd gear switch may cause Code 26 to set intermittently.