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

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For appropriate wiring diagram, see WIRING DIAGRAMS at end of 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 fault messages.

BUS BIAS LEVEL TOO LOW
BUS BIAS LEVEL TOO HIGH
BUS (+) OPEN
BUS (-) OPEN
BUS (+) & (-) OPEN
1. Ignition off during bus test is the most common cause for these messages. Turn ignition on, engine off. Disconnect DRB-II. Using an external voltmeter, check voltage between CCD data link connector CCD bus positive circuit (Violet/Brown wire) and ground. If voltage is not 2.3-2.6 volts, go to step 4).
2. If voltage is 2.3-2.6 volts, check voltage between CCD data link connector CCD bus negative circuit (White/Black wire) and ground.
3. If voltage is not 2.3-2.6 volts, go to next step. If voltage is 2.3-2.6 volts, replace DRB-II cable or cartridge as necessary. Perform VERIFICATION PROCEDURE VER-1.
4. Turn ignition off, and disconnect Body Control Module (BCM). BCM is located behind right kick panel. Check resistance between BCM pins No. 7 and 8. See Figure . If resistance is not 100-140 ohms, replace BCM. Perform VERIFICATION PROCEDURE VER-1.
5. If resistance is 100-140 ohms, check resistance of CCD bus positive circuit (Violet/Brown wire) between BCM Bone connector terminal No. 8 and CCD data link connector. If resistance is more than 5 ohms, repair open circuit in Violet/Brown wire. Perform VERIFICATION PROCEDURE VER-1.
6. If resistance is less than 5 ohms, check resistance between BCM Bone connector terminal No. 7 and CCD data link connector CCD bus negative circuit (White/Black wire). If resistance is more than 5 ohms, repair open circuit in White/Black wire. Perform VERIFICATION PROCEDURE VER-1.
7. If resistance is less than 5 ohms, disconnect Powertrain Control Module (PCM). PCM is located under air box in engine compartment. Using an external ohmmeter, check resistance between PCM pins No. 26 and 46. If resistance is not 100-140 ohms, replace PCM. Perform VERIFICATION PROCEDURE VER-1.
8. If resistance is 100-140 ohms, check resistance between PCM connector terminal No. 26 and CCD data link connector CCD bus positive circuit (Violet/Brown wire). If resistance is more than 5 ohms, repair open circuit in Violet/Brown wire. Perform VERIFICATION PROCEDURE VER-1.
9. If resistance is less than 5 ohms, check resistance between PCM connector terminal No. 46 and CCD data link connector CCD bus negative circuit (White/Black wire). If resistance is more than 5 ohms, repair open circuit in White/Black wire. Perform VERIFICATION PROCEDURE VER-1.
10. If resistance is less than 5 ohms, check resistance between BCM Bone connector terminal No. 8, CCD bus positive circuit (Violet/Brown wire), and ground. If resistance is more than 5 ohms, repair short to ground in Violet/Brown wire. Perform VERIFICATION PROCEDURE VER-1.
11. If resistance is less than 5 ohms, check resistance between BCM Bone connector terminal No. 7, CCD bus negative circuit (White/Black wire), and ground.
12. If resistance is more than 5 ohms, repair short to ground in White/Black wire. Perform VERIFICATION PROCEDURE VER-1. If resistance is less than 5 ohms, replace BCM. Perform VERIFICATION PROCEDURE VER-1.