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

WARNING: This page is about a different car, the 1995 Plymouth Neon, 1995 Eagle Talon, 1995 Dodge Neon, 1995 Dodge Avenger, and 1995 Chrysler Sebring. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION in BODY CONTROL COMPUTER. For wiring diagrams, see article in ENGINE PERFORMANCE:

WIRING DIAGRAMS - 2.0L & 2.4L
WIRING DIAGRAMS - 2.5L V6
After each repair, perform TEST VER-1 .

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

NOTE: Ignition off during bus test is most common cause for this trouble code.
1. This test applies to FJ22 and F24S bodies only. If ignition was off during BUS test, turn ignition on. If ignition was on during BUS test, turn ignition off and disconnect scan tool from 12-pin Data Link Connector (DLC). Turn ignition on. Using scan tool in voltmeter mode, check voltage on 12-pin DLC terminal No. 7 (Black/Dark Blue wire). If voltage is not 2.3-2.6 volts, go to step 3).
2. If voltage is 2.3-2.6 volts, check voltage on 12-pin DLC terminal No. 8 (White/Dark Blue wire). 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 scan tool as necessary.
3. Turn ignition off and disconnect Transmission Control Module (TCM). Using an external ohmmeter, check resistance between TCM terminals No. 5 and No. 44. If resistance is not 100-140 ohms, replace TCM.
4. If resistance is 100-140 ohms, check resistance of Black/Dark Blue wire between 12-pin DLC terminal No. 7 and TCM connector terminal No. 43. If resistance is more than 5 ohms, repair open Black/Dark Blue wire.
5. If resistance is less than 5 ohms, check resistance of White/Dark Blue wire between 12-pin DLC terminal No. 8 and TCM terminal No. 4. If resistance is more than 5 ohms, repair open White/Dark Blue wire.
6. If resistance is less than 5 ohms, check resistance of Black/Dark Blue wire between TCM connector terminals No. 5 and No. 43. If resistance is more than 5 ohms, repair open Black/Dark Blue wire.
7. If resistance is less than 5 ohms, check resistance of White/Dark Blue wire between TCM connector terminals No. 4 and No. 44. If resistance is more than 5 ohms, repair open White/Dark Blue wire.
8. If resistance is less than 5 ohms, reconnect scan tool to DLC and turn ignition on. Using scan tool in voltmeter mode, check voltage on TCM connector terminal No. 8 (Black/Red wire). If voltage is less than 10 volts, repair open Black/Red wire.
9. If voltage is more than 10 volts, turn ignition off. Using scan tool in ohmmeter mode, check resistance of TCM connector terminal No. 57 (Black wire). If resistance is more than 5 ohms, repair open Black wire. If resistance is less than 5 ohms, replace TCM.