Test 12J - Bus Bias Level Or Bus (+/-) Open (Wrangler)

WARNING: This page is about a different car, the 1995 Jeep Wrangler, 1995 Jeep Grand Cherokee, and 1995 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION in this article. For appropriate wiring diagram, see WIRING DIAGRAMS section at the end of this article.

CAUTION: Always turn ignition switch to OFF position prior to disconnecting or connecting any module connector.

This test covers following BUS BIAS LEVEL OR BUS (+/-) OPEN trouble codes. Ignition off during BUS test is the most common cause for these messages.

BUS BIAS LEVEL TOO LOW
BUS BIAS LEVEL TOO HIGH
BUS (+) OPEN
BUS (-) OPEN
BUS (+) & BUS (-) OPEN
1. If ignition was off, turn ignition on (engine off). If ignition was on, disconnect scan tool from Data Link Connector (DLC). Using an external voltmeter, check voltage between Data Link Connector (DLC), CCD BUS positive circuit (White/Violet wire) and ground. If voltage is not 2.3-2.6 volts, go to step 3).
2. If voltage is 2.3-2.6 volts, check voltage between DLC, CCD BUS negative circuit (Orange wire) and ground. If voltage is not 2.3-2.6 volts, go to next step. If voltage is 2.3-2.6 volts, replace scan tool cable or cartridge as necessary. Perform TEST VER-1 .
3. Turn ignition off. Disconnect Controller Anti-Lock Brake (CAB) module connector, if equipped. Check resistance between CAB pins No. 23 and 42. If resistance is not 100-140 ohms, replace CAB. Perform TEST VER-1 .
4. If resistance is 100-140 ohms, check resistance of CCD BUS positive circuit (White/Violet wire) between CAB connector terminal No. 23 and DLC. If resistance is more than 5 ohms, repair open White/Violet wire. Perform TEST VER-1 .
5. If resistance is less than 5 ohms, check resistance of CCD BUS negative circuit (Orange wire) between CAB connector terminal No. 42 and DLC. If resistance is more than 5 ohms, repair open Orange wire. Perform TEST VER-1 .
6. If resistance is less than 5 ohms, reconnect scan tool. Using scan tool in voltmeter mode, check voltage on CAB connector terminal No. 53, fused ignition switch output circuit (Yellow/Dark Green wire). If voltage is less than 10 volts, repair open Yellow/Dark Green wire. Perform TEST VER-1 .
7. If voltage is more than 10 volts, turn ignition off. Using scan tool in ohmmeter mode, check resistance of CAB connector terminal No. 1, ground circuit (Black wire). If resistance is more than 5 ohms, repair open to ground in Black wire. Perform TEST VER-1 . If resistance is less than 5 ohms, replace CAB module. Perform TEST VER-1 .