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

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . 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, using an external voltmeter, check voltage between Data Link Connector (DLC), CCD BUS positive circuit (Violet/Brown 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 (White/Black 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 Powertrain Control Module (PCM) connector. Using an external ohmmeter, check resistance between PCM pins No. 26 and 46. If resistance is not 100-140 ohms, replace PCM. Perform TEST VER-1.
4. If resistance is 100-140 ohms, check resistance of CCD BUS positive circuit (Violet/Brown wire) between PCM connector terminal No. 26 and DLC. If resistance is more than 5 ohms, repair open Violet/Brown wire. Perform TEST VER-1.
5. If resistance is less than 5 ohms, check resistance of CCD BUS negative circuit (White/Black wire) between PCM connector terminal No. 46 and DLC. If resistance is more than 5 ohms, repair open White/Black wire. Perform TEST VER-1.
6. If resistance is less than 5 ohms, disconnect Body Control Module (BCM) connectors. Check resistance between BCM pins No. 7 and 20. See Figure . If resistance is not 100-140 ohms, replace BCM. Perform TEST VER-1.
7. If resistance is 100-140 ohms, check resistance between BCM Blue connector terminal No. 7, CCD BUS positive circuit (Violet/Brown wire) and DLC. If resistance is more than 5 ohms, repair open Violet/Brown wire. Perform TEST VER-1.
8. If resistance is less than 5 ohms, check resistance between BCM Blue connector terminal No. 20, CCD BUS negative circuit (White/Black wire) and DLC. If resistance is more than 5 ohms, repair open White/Black wire. Perform TEST VER-1.
9. If resistance is less than 5 ohms, check resistance between DLC, CCD BUS positive circuit (Violet/Brown wire) and ground. If resistance is more than 5 ohms, repair open Violet/Brown wire. Perform TEST VER-1.
10. If resistance is less than 5 ohms, check resistance between DLC, CCD BUS positive circuit (Violet/Brown wire) and ground. If resistance is less than 100 ohms, repair short to ground in Violet/Brown wire. Perform TEST VER-1.
11. If resistance is more than 100 ohms, check resistance between DLC, CCD BUS negative circuit (White/Black wire) and ground. If resistance is less than 100 ohms, repair short to ground in White/Black wire. Perform TEST VER-1.
12. If resistance is more than 100 ohms, reconnect scan tool. Using scan tool in voltmeter mode, check voltage on BCM Blue connector terminal No. 8, fused battery voltage circuit (Pink wire). If voltage is less than 10 volts, repair Pink wire as necessary. Perform TEST VER-1.
13. If voltage is more than 10 volts, check voltage on BCM Blue connector terminal No. 11, fused ignition switch output circuit (Dark Blue wire). If voltage is less than 10 volts, repair Dark Blue wire as necessary. Perform TEST VER-1.
14. If voltage is more than 10 volts, turn ignition off. Using scan tool in ohmmeter mode, check resistance of BCM Blue connector terminal No. 19, ground circuit (Black/Light Green wire). If resistance is more than 15 ohms, repair open to ground in Black/Light Green wire. Perform TEST VER-1.
15. If resistance is less than 15 ohms, check resistance between BCM case and ground. If resistance is more than 5 ohms, repair BCM case ground as necessary. Perform TEST VER-1. If resistance is less than 5 ohms, replace BCM. Perform TEST VER-1.