2008 Dodge Charger 2.7 L no start problem with bus communication fault code :

This vehicle wont start and has bus active fault code. Using a scanner, can communicate with TIPM, Instrument cluster and steerting column modules. I probed the TIPM module and is showing voltages at all pins 11, 12, 7, 8, 5 and 6 showing 2.39 and 2.59 voltages respectively. The PCM has good reference voltages at the pins but was replaced anyway by another mechanic. The engine cranks but does not start.

Fault code found:

U0001-CAN C Bus Active

DIAGNOSTIC GUIDE

Shown here is the DCL pin connector and module wiring diagram so we can analyze the 2008 Dodge Charger bus line wirings:

2008 Dodge Charger no        start bus wiring diagram

TIPM module: (seen on top right)

Again looking at the computer bus lines, the Can C wirings starts at pin14 and pin6 at the DLC then goes to the TIMP pins 11 and 12. The TIMP is also the gateway module for all the oher modules. Or job is to find the voltage readings at DLC and compare them at TIMP pins. Since the readings found coming at pins 7 and 8 and 5 and 6 which were 2.39 and 2.59 respectively, it is safe to say that the TIMP module is defective internally.

Another way to check this is to set your voltmeter: You just turn your voltmeter in DMM to DC, set it to auto ranges and you can measure the fluctuating voltages at pins 7,8,5 and 6. The Can H is about 2.5 to 3.5 volts whereas Can Lo is between 1.5 to 2.5 volts. If the reading is way up, it means it is shorted to power or if way down, is shorted to ground.

To check for defective modules; lets say your reading at the pins of TIMP is way out, you can disconnect pins 35 and 34 of PCM and see if reading at TIMP goes to normal. If not, reconnect and proceed to disconnect pins L2 and H2 for the TCM module, pins 13 and 12 of ABS module. pins 4 and 5 of the AC Heater Control module. Any readings that makes the readings of the TIMP module normal is the culprit.

Note:

The output modules shown here is only 3 per each CanB and CanC Bus circuits. The actual count is 1-2 dozen modules for each circuits. This is for demo purpose only.

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