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Some Info to help you amass tech stuff
TSBs & Wiring Diagrams
89 BII
http://www.bbbind.com/free_tsb.html
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The RABS consists of the following components:
http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c152800783e0
1. RABS module (1989-90)-located in the dash under the IP panel mount on a brace, center of panel area. The (RABS) module for 1987-88 model year is located behind an access cover in back of the driver's side door pillar.
2. Dual Solenoid Electro-Hydraulic Valve is located 5 in. (127mm) rearward of the No. 1 crossmember on the inboard side of the LH frame rail.
3. Speed Sensor and Exciter Ring-located in the rear differential housing.
4. Yellow REAR ANTI-LOCK Warning Light-located in the instrument cluster.
5. RABS Diagnostic Connector-located on the main wire bundle inside of cab under the dash, slightly rearward driver side.
6. Diode/Resistor Element-located in the master cylinder fluid level sensor wiring harness on the left splash apron.
7. Sensor test Connector-located under the hood slightly rearward the washer bottle.
http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c1528007846c
System Self-test
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The RABS module preforms system tests and self-tests during startup and normal operation. The valve, sensor and fluid level circuits are monitored for proper operation. If a fault is found, the RABS will be deactivated and the REAR ANTI LOCK light will be lit until the ignition is turned OFF. When the light is lit, the diagnostic flashout code may be obtained. Under normal operation, the light will stay on for about 2 seconds while the ignition switch is in the ON position and will go out shortly after. A flash code may be obtained only when the yellow light is ON. Before reading the code, drive the vehicle to a level area and place the shift lever in the PARK or NEUTRAL position. Keep the vehicle ignition ON.
TO OBTAIN THE FLASH CODE:
1. Locate the RABS diagnostic connector (orange/black wire) and attach a jumper wire to it and ground it to the chassis.
2. Quickly remove the ground. When the ground is made and then removed, the RABS light will begin to flash.
3. The code consists of a number of short flashes and ends with a long flash. Count the short flashes and include the following long flash in the count to obtain the code number. Example 3 short flashes and one long flash indicated Code No. 4. The code will continue until the ignition is turned OFF . Refer to the flashcode diagnosis charts for further instructions.
http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c15280078472
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