Engine Control - CEL Light ON with No Codes Stored
88chevy25Number: 88-357-6E
Section: 6E
Date: Nov., 1988
Subject: "SERVICE ENGINE SOON" LIGHT COMES ON
NO DIAGNOSTIC CODE STORED
Model and Year: 1988 G20 VANS WITH 6.2L ENGINE (VIN CODE C)
TO: ALL CHEVROLET DEALERS
Some instrument panel harness assemblies released for the 1988 G20 vans equipped with LH6 engines (6.2L diesel), have circuits #439 and #440 interchanged at the fuse block connector. These circuits feed the 6.2L Electronic Control Module (ECM) ignition and battery inputs. With the circuits interchanged, the ECM will not store diagnostic codes.
FIGURE 1:
FIGURE 2:
This condition may be corrected by switching circuit #439, Fuse Label "ECM B" (pink with black stripe) and circuit #440, Fuse Label "ECM I" (orange) at the fuse block connector as shown in Figures 1 and 2.
INSTRUCTIONS: (See Figures 1 and 2)
1. Disconnect the negative battery cable.
2. Remove the two dash panel connector block screws and remove the fuse block connector. The fuse block connector is located on the left side of the dash panel.
3. Remove the two screws in the fuse block connector and separate.
4. Using a small screwdriver, pry down on the lock tangs and remove terminal #439, Fuse Label "ECM B" and #440, Fuse Label "ECM I".
5. Interchange the terminals as indicated and reinstall by prying out the lock tangs and inserting the terminals into the connector.
6. Using the two screws previously removed, reconnect the fuse block connector.
7. Using the two screws previously removed, reattach the fuse block connector to the dash panel.
8. Reconnect the negative battery cable.
The instrument panel harness assemblies should be reworked only if the vehicle comes into a dealership for ECM diagnostic related service work. This condition will not affect the vehicle's performance.
If the "Service Engine Soon" light comes on during vehicle operation the diagnostic trouble code will be erased the first time the key is turned off. In order to obtain a diagnostic trouble code, (while wires are interchanged leave the engine running.
All 1988 vehicles built prior to the VIN number listed below are affected:
2GBEG25H2J4135825
For repair to vehicles under warranty use:
Labor Op: T7750
Labor Time: 0.3 Hr.
These diagrams indicate fuse block before correction.