2006 Impala 3.5 stalled, got towed in

07-22-2015, 09:50 AM
When the driver tried to restart, it almost started he said and then all he smelt was rotten eggs. I pulled these codes off:
U0121-Lost Commmunication with ABS Control Module
P0106- Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0121-Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem
U0140- Lost Communication with Body Control Module

It had "Engine Reduced Power" in the DIC. In past this has been a defective pedal position sensor, I watched scan data as I swept the throttle and it did indeed appear to be not functioning properly. Thought cool..ordered another sensor, installed it, now the scanner showed it working right. I also switched out the throttle body with a known good used one at the time when changed pedal sensor. Cleared codes and attempted to start..nope..turns over nice, but not firing up. Checked fuel pressure and its good. Had someone turn over engine while I had an inline spark tester connected, no spark. Checked out the coil pack and its good.

followed up the body control module code and in the diagnostic fault chart, U0140 is under Open/High Resistance. Went in and disconnected C3 on BCM, acutally removed all connectors and removed BCM for the moment. Resistance on Pin 10 of C3 was 10 Meg, high resistance but not an open. Not sure what the expected resistance value of that should be..
Problem is going back from there, no idea where that wire runs back to, its like working on a space shuttle or something..so many wires etc.

Any suggestions welcome!

07-24-2015, 09:19 AM
Update: Turns out when I checked the Ignition Coil Pack, I did the ohm check on it per specifications and did a power and ground check at the connector...well I thought I had, seems I must have skipped over the ground check after doing the power! For when I ended up not getting anywhere with testing various things I went back to basics and started over, cleared all codes, checked for power and ground at the coil pack connector and there was no ground at the black/white wire (removed connector and ran test light from bat(+) to ground pin).

Ran a spliced in jumper wire from ground pin to bat(-) connector and she fired right up!

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