No Response From Controller Anti-Lock Brake

Possible Causes:

• No Response From CAB
• Replace Fuse No. 17
• Fused Ignition Switch Output Circuit Shorted To Ground
• Ground Circuit Open
• Open Fused Ignition Switch Output Circuit
• Controller Anti-Lock Brake (CAB) Module
• PCI Bus Circuit Open
• Body Control Module

Testing

1. Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select BODY, then BODY COMPUTER. If scan tool communicates with Body Control Module (BCM), go to next step. If scan tool does not communicate with BCM, perform BUS +/- SIGNALS OPEN OR NO RESPONSE FROM BODY CONTROL MODULE  test.
2. Turn ignition off. Remove and inspect fuse No. 17 (10-amp) in junction block. Fuses are identified on inside of left instrument panel end cap. If fuse is open, go to next step. If fuse is okay, install fuse and go to step  4 .
3. Replace fuse No. 17. Turn ignition on. Remove and inspect fuse No. 17 (10-amp) in junction block. If fuse is open, repair fused ignition switch circuit (White/Violet wire) between Controller Anti-Lock Brake (CAB) connector terminal No. 23 and junction block. If fuse is okay, fault may be intermittent. Check fused ignition switch circuit for intermittent short to ground. See WIRING DIAGRAMS  .
4. Ensure ignition is off. Disconnect Controller Anti-Lock Brake (CAB) connector. Measure resistance between ground and CAB connector terminals No. 1 and 16, ground circuits (Black wires). See Figure . If resistance is less than 5 ohms on both circuits, leave CAB connector disconnected and go to next step. If resistance is 5 ohms or more on either circuit, repair open in Black wire(s).
5. Ensure fuse No. 17 is installed in junction block. Turn ignition on. Using a 12-volt test light connected to ground, probe CAB connector terminal No. 23, fused ignition switch output circuit (White/Violet wire). If test light illuminates, go to next step. If test light does not illuminate, repair open in White/Violet wire.
6. Turn ignition on. Using scan tool, attempt to communicate with other modules. If scan tool communicates with other modules, go to next step. If scan tool does not communicate with other modules, perform PCI BUS COMMUNICATION FAILURE  test.
NOTE: Steps  7 - 9 are written specifically for use with Chrysler's Diagnostic Readout Box (DRBIII(R)) scan tool.
7. Turn ignition off. Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Connect Red and Black leads and Cable-To-Probe Adapter (CH7062) to scope input cable. Go to next step.
8. Using scan tool, select DRB STANDALONE, LAB SCOPE, LIVE DATA, then 12-VOLT SQUARE WAVE. Press F2 for scope. Press F2 again and use down arrow to set voltage range to 20 volts. Press F2 again. Go to next step.
9. Connect Black lead to chassis ground. Connect Red lead to CAB connector terminal No. 20, PCI bus circuit (Violet/Yellow wire). Turn ignition on. Observe voltage display on scan tool lab scope. If voltage pulses from zero to about 7.5 volts, replace CAB. See Figure -Figure . See DISC - CONCORDE, INTREPID & 300M article in BRAKES. If voltage does not pulse from zero to about 7.5 volts, leave CAB connector disconnected and go to next step.
10. Turn ignition off. Disconnect BCM connector C3. Measure resistance of PCI bus circuit (Violet/Yellow wire) between BCM connector terminal No. 2 and CAB connector terminal No. 5. See Figure and Figure . If resistance is less than 5 ohms, replace BCM. See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. If resistance is 5 ohms or more, repair open in Violet/Yellow wire.