Brakes - (4WAL) False Codes Set

90chevy24
GMC NUMBER: 91-5E-19

GROUP: 5E Anti-Lock Brakes
DATE: September, 1990

CORPORATE
NUMBER: 065017
SUBJECT: FALSE CODES 41, 42, 43, 44, 46, 48, 51, 52, 53, AND 54

MODELS: 1990-91 M/L VANS AND 1991 S/T 4 DOOR UTILITY VEHICLES EQUIPPED WITH 4 WHEEL ANTI-LOCK BRAKES
Some 1990-91 M/L vans and 4 door S/T utility vehicles may experience a condition in which the ANTI-LOCK light is illuminated and the anti-lock feature of the brake system is deactivated without a true malfunction of the, 4WAL module.






The condition may cause one or any combination of the following trouble codes to be falsely set and stored in the Electro Hydraulic Control Unit (EHCU) memory.

Figure 1: S/T Truck:

Figure 2: M/L Van:

The root cause of this condition is a poor connection at the vehicle junction block located against the vehicle cowl on the left side of the vehicle (see Figures 1 and 2). It a vehicle exhibits the above codes technicians should inspect the junction block connector for looseness and corrosion or contaminants. Any of these will cause a poor connection. Once the connector has been cleaned, check all male to female connections to assure that all female sockets hold the male inserts securely.

When the Junction block is secure, clear the codes from the EHCU and run a function test using Tech 1 to verity the repair.