Test 12E - 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 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 DRB. Using external voltmeter, check voltage between CCD 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 CCD 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 DRB cable or cartridge as necessary. Perform TEST VER-1.
  3. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector. PCM is located between DLC and battery, on fenderwell. 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 CCD DLC. If resistance is more than 5 ohms, repair open circuit in 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 CCD DLC. If resistance is more than 5 ohms, repair open circuit in White/Black wire. Perform TEST VER-1.
  6. If resistance is less than 5 ohms, disconnect Body Control Module (BCM) connectors. BCM is located behind knee panel below dashboard. Check resistance between BCM pins No. 14 and 15. 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 Blue BCM connector terminal No. 14 and CCD DLC, CCD BUS positive circuit (Violet/Brown wire). If resistance is more than 5 ohms, repair open circuit in Violet/Brown wire. Perform TEST VER-1.
  8. If resistance is less than 5 ohms, check resistance between Blue BCM connector terminal No. 15 and CCD DLC, CCD BUS negative circuit (White/Black wire). If resistance is more than 5 ohms, repair open circuit in White/Black wire. Perform TEST VER-1.
  9. If resistance is less than 5 ohms, check resistance between CCD DLC, 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 TEST VER-1.
  10. If resistance is less than 5 ohms, check resistance between CCD DLC, CCD BUS negative circuit (White/Black wire) and ground. If resistance is more than 5 ohms, repair short to ground in White/Black wire. Perform TEST VER-1.
  11. If resistance is less than 5 ohms, reconnect DRB. Using DRB in voltmeter mode, check voltage on Blue BCM connector terminal No. 16, fused battery feed circuit (Pink wire). If voltage is not more than 10 volts, repair Pink wire as necessary. Perform TEST VER-1.
  12. If voltage is more than 10 volts, check voltage on Blue BCM connector terminal No. 12, fused ignition feed run/start circuit (Dark Blue/White wire). If voltage is not more than 10 volts, repair Dark Blue/White wire as necessary. Perform TEST VER-1.
  13. If voltage is more than 10 volts, turn ignition off. Using DRB in ohmmeter mode, check resistance of Blue BCM connector terminal No. 13, 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.
  14. If resistance is less than 15 ohms, check resistance of BCM case 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.