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

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

• BUS BIAS LEVEL TOO LOW
• BUS BIAS LEVEL TOO HIGH
• BUS (+) OPEN
• BUS (-) OPEN
• BUS (+) & (-) OPEN
  1. Turn ignition on, engine off. Disconnect DRB. Using an external voltmeter, check voltage between chassis ground and DLC terminal No. (Violet/Brown 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 between chassis ground and DLC terminal No. 3 (White/Black wire). If voltage is not 2.3-2.6 volts, go to next step. If voltage is 2.3-2.6 volts, replace DRB cable or cartridge as necessary.
  3. Turn ignition off and disconnect Powertrain Control Module (PCM). PCM is located under air cleaner in engine compartment. Using an external ohmmeter, check resistance between PCM terminals No. 26 and 46. If resistance is not 100-140 ohms, replace PCM.
  4. If resistance is 100-140 ohms, check resistance of Violet/Brown wire between PCM connector terminal No. 26 and DLC terminal No. 4. If resistance is more than 5 ohms, repair open Violet/Brown wire.
  5. If resistance is less than 5 ohms, check resistance of White/Black wire between PCM connector terminal No. 46 and DLC terminal No. 3. If resistance is more than 5 ohms, repair open White/black wire.
  6. If resistance is less than 5 ohms, disconnect Body Control Module (BCM). BCM is located behind right kick panel. Check resistance between BCM Bone terminals No. 7 and No. 8. See Figure . If resistance is not 100-140 ohms, replace BCM.
  7. If resistance is 100-140 ohms, check resistance of Violet/Brown wire between BCM Bone connector terminal No. 8 and DLC terminal No. 4. If resistance is more than 5 ohms, repair open Violet/Brown wire.
  8. If resistance is less than 5 ohms, check resistance of White/black wire between BCM Bone connector terminal No. 7 and DLC terminal No. 3. If resistance is more than 5 ohms, repair open White/Black wire.
  9. If resistance is less than 5 ohms, check resistance between chassis ground and BCM Bone connector terminal No. 8 (Violet/Brown wire). If resistance is less than 100 ohms, repair short to ground in Violet/Brown wire.
  10. If resistance is more than 100 ohms, check resistance between chassis ground and BCM Bone connector terminal No. 7 (White/Black wire). If resistance is less than 100 ohms, repair short to ground in White/Black wire.
  11. If resistance is more than 100 ohms, reconnect DRB. Using DRB in voltmeter mode, check voltage on BCM Bone connector terminal No. 19 (Pink wire). If voltage is less than 10 volts, repair Pink wire as necessary.
  12. If voltage is more than 10 volts, check voltage on BCM Bone connector terminal No. 13 (Dark Blue/White wire). If voltage is less than 10 volts, repair open Dark Blue/White wire.
  13. If voltage is more than 10 volts, using DRB in ohmmeter mode, check resistance of Bone connector terminal No. 21 (Black wire). If resistance is more than 15 ohms, repair open Black wire. If resistance is less than 15 ohms, replace BCM.