If the vehicle is equipped with air bag (SIR or SRS) system, always properly disable the system before commencing work on the ABS system.
Certain components within the RWAL system are not intended to be serviced or repaired. Only those components with removal & Installation procedures should be serviced.
Do not use rubber hoses or other parts not specifically specified for the RWAL system. When using repair kits, replace all parts included in the kit. Partial or incorrect repair may lead to functional problems.
Lubricate rubber parts with clean, fresh brake fluid to ease assembly. Do not use lubricated shop air to clean parts; damage to rubber components may result.
Use only brake fluid from an unopened container. Use of suspect or contaminated brake fluid can reduce system performance and/or durability.
A clean repair area is essential. Perform repairs after components have been thoroughly cleaned; use only denatured alcohol to clean components. Do not allow components to come into contact with any substance containing mineral oil; this includes used shop rags.
The RWAL ECU is a microprocessor similar to other computer units in the vehicle. Insure that the ignition switch is
before removing or installing controller harnesses. Avoid static electricity discharge at or near the controller.
Never disconnect any electrical connection with the ignition switch
unless instructed to do so in a test.
Always wear a grounded wrist strap when servicing any control module or component labeled with a Electrostatic Discharge (ESD) symbol.
Avoid touching module connector pins.
Leave new components and modules in the shipping package until ready to install them.
To avoid static discharge, always touch a vehicle ground after sliding across a vehicle seat or walking across carpeted or vinyl floors.
Never allow welding cables to lie on, near or across any vehicle electrical wiring.
Do not allow extension cords for power tools or droplights to lie on, near or across any vehicle electrical wiring.
See Figures 1, 2, 3 and 4
Before reading trouble codes, perform the general system inspection according to the chart. This test will aid in separating RWAL system problems from common problems in the hydraulic brake system. The diagnostic circuit check will direct the reading of trouble codes as necessary.
Fig. Fig. 1: Preliminary Rear Wheel Anti-Lock (RWAL) brake system diagnosis-chart 1 of 3
Fig. Fig. 2: Preliminary Rear Wheel Anti-Lock (RWAL) brake system diagnosis-chart 2 of 3
Fig. Fig. 3: Preliminary Rear Wheel Anti-Lock (RWAL) brake system diagnosis-chart 3 of 3
Fig. Fig. 4: RWAL brake system electrical schematic
See Figures 5, 6 and 7
Since the trouble codes are cleared whenever the ignition switch is turned
OFF, avoid turning the switch
if you intend to read the codes.
The RWAL ECU will assign a code to the first fault found in the system. If there is more than 1 fault, only the first recognized code will the stored and transmitted.
Fig. Fig. 5: To initiate the warning light flash-out of brake-related trouble codes, connect terminals 3 and 5 of the monitor coupler with a jumper wire for at least 2 seconds
Fig. Fig. 6: Example of how a typical Diagnostic Trouble Code (DTC) is flashed out by the brake warning light, located in the instrument cluster
Fig. Fig. 7: Rear Wheel Anti-Lock (RWAL) brake system Diagnostic Trouble Codes (DTCs)
Trouble codes may be read by connecting a jumper wire from terminal
to terminal 5 on the diagnostic monitor for at least 2 seconds, then releasing it. The fault code(s) will be displayed through the flashing of the BRAKE warning lamp on the dash. The terminals must be connected for about 2 seconds before the display begins. The display will begin with 1 long flash followed by shorter ones-count the long flash as part of the display.
Sometimes the first display sequence will be inaccurate or short; so it is a good idea to allow the code flash-out sequence to cycle a couple of times while you read the codes.
Stored trouble codes are cleared every time the ignition switch is turned