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sprinkles08, ASE Certified Technician
Category: Chevy
Satisfied Customers: 22684
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I have a 2006 Malibu SS with the 3.9L, MIL, T/C lamp, Engine

Customer Question

Hi. I have a 2006 Malibu SS with the 3.9L, MIL, T/C lamp, Engine Power Reduced message. Initial codes were for intake related issues.
JA: Thanks. Can you give me any more details about your issue?
Customer: Car will start but not run or maintain idle.
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Submitted: 1 year ago.
Category: Chevy
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

What P codes are setting?

Has anything been done to try to repair the issues?

Customer: replied 1 year ago.
Initially there were numerous throttle and fuel delivery codes. The one throwing the MIL was P2135 for the throttle body. I have inspected the APS connections as well as the TPS. I removed the air boot and inspected the throttle body for carbon buildup or any obvious restrictions and found none. I was thinking I have a bad TPS and would be replacing the throttle body but after reset of the codes I started getting a different response. I have a laundry list of codes coming up now without attempting to crank. They all appear to be relating to communication problems. I was having lights flash on the dash and error appearing in the odometer spot and my code reader was having intermittent communication failure. The car will crank but not maintain an idle and stalls after 10 sec or so. I am beginning to suspect a faulty PCM but wonder if there is anything else I should check. I plan to inspect the connections to the PCM and the wiring harness for anything obvious and maybe check the electrical grounding but I'm not sure of all the grounding locations and which would be most likely fault if this is the issue. Codes were C0242, C0561, U2100, U0073, P0575, P0703, P0856, P2119, P2135, U0101, U0140. Pretty impressive bunch huh?
Expert:  sprinkles08 replied 1 year ago.

You've cleared the codes and these all come back?

Customer: replied 1 year ago.
Expert:  sprinkles08 replied 1 year ago.

The P2119 and 2135 are both throttle body related and are going to require throttle body replacement.

The rest of the codes are for communication issues. The modules communicate with each other through two separate wired networks and these codes are setting because communication isn't possible. The problem may be an internal failure in any module on the network dragging voltage high or low, or it could be a wiring issue. If the circuit shorts to power or ground then it will prevent communication. This is going to require testing at the time communication is not possible. The bus will need to be tested to see if it's shorted high or low, modules can be disconnected one at a time to see when the short goes away or communication with others returns. If disconnecting all modules doesn't remove the short then there is a wiring issue. If just one module isn't communicating then it's bus voltage can be compared to others, if the same then that module can be condemned.

Customer: replied 1 year ago.
after inspecting the PCM and wiring there should I be resetting codes and disconnecting one module at a time to see if communication with the other modules resumes? Would a failure in a module or short be causing the intermittent communication failure between my code reader and the main computer?
Expert:  sprinkles08 replied 1 year ago.

A scan tool would be needed for diagnosis. A code reader will just read fault codes from the engine controller, a scan tool is going to be necessary to check for communication with all modules.

Customer: replied 1 year ago.
I have the Bosch 1150 ... it's not just a code reader but will it do what needs to be done?
Expert:  sprinkles08 replied 1 year ago.

You may be able to get by with that if you were having trouble getting it to communicate. An actual scan tool would be much preferred but is a multi thousand dollar piece of equipment.