ECM - Revised Code 26 (Temperature Light) Chart
89Pontiac24Bulletin Number: 90-6-11
Reference Number: 916529
Publish Date: 11/89
Subject: SERVICE MANUAL UPDATE-SUCTION 6E3- DRIVEABILITY AND EMISSIONS REVISED CODE 26 FACING PAGE, CHART
Models
Affected: 1990 GRAND AM 2.3L (VIN D, A)
This bulletin serves to update Code 26 (Page 1 of 2) chart and facing page in Section 6E3 "Driveability And Emissions" in the 1990 Service Manual with 2.3L Grand Am (VIN D and A) applications.
Adding temperature light Circuit 35 DK GRN, pin GF7.
CODE 26
(Page 1 of 3)
QUAD-DRIVER (QDM) CIRCUIT 2.3L (VIN D & A) "N" CARLINE (PORT)
Circuit Description:
The ECM controls most components with electronic switches which complete a ground circuit when turned "ON." These switches are arranged in groups of 4, called Quad-Driver Modules (QDM's) which can independently control up to 4 outputs (ECM terminals), although not all outputs are used. When an output is "ON," the terminal is grounded and its voltage normally will be low. When an output is "OFF," its terminal voltage normally will be high, except for the TCC, as noted below, which depends on the brake and 2nd gear TCC switches. QDM's are fault protected. If a relay or solenoid coil is shorted, having very low of zero resistance, or if the control side of the circuit is shorted to voltage, it would allow too much current into the QDM. The QDM senses this and the output turns "OFF" or its internal resistance increases to limit current flow and protect the QDM. The result is high output terminal voltage when it should be low. If the circuit from B + or the component is open, or the control side of the circuit is shorted to ground, terminal voltage will be low, even when output is commanded "OFF." Either of these conditions is considered to be a QDM fault. *SEE NOTE BELOW! Each QDM has a separate fault line to indicate the presence of a current fault to the ECM's central processor. A "Scan" tool displays the status of each of these fault lines as "Low" = OK, "High" = Fault*. Because of the brake and 2nd gear switches in the TCC circuit, Code 26 is set under different conditions for QDM A and QDM B as follows:
^ QDM A fault line = "High" for 20 seconds or more.
^ QDM B fault line = "High" for 20 seconds or more and
- Brake switch signal indicates brake switch is closed and 2nd gear state switch indicates transaxle is in 2nd or 3rd gear. OR
- TCC is commanded "ON."
NOTE: QDM B fault line on an automatic transaxle car will normally be "High" when the car is stopped. The ECM ignores the QDM B fault line except under conditions noted above.