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Discussion Starter · #1 · (Edited by Moderator)
My daughters car started giving a warning of Service Steering. The gauges went to all zero. I scanned the codes and it was ECM P0089, ECM P0700 and TCM:U0073.

She broke down close to a GMC dealer so we replaced the Red Battery cable and fuse distribution block on the battery.
It seemed to work for the ride home. Then started again a day later. This set off a new set of codes ECM P0700, ECM:U0101 and TCM:U0073. I ordered the replacement negative cable. Ordered the new short red cable to the block. THis was the one everyone is using to solve the issue. Removed all ECM and TCM connectors and sprayed with electronic cleaner and blew out with air. Cleaned the 3 ground points in front of the battery.

The car drove fine for several days. Did it again today and she is stranded. Had her try clearing the codes so it would shift properly. Check engine light keeps coming right back and car wont move well without a lot of throttle.

Battery is 4 months old and Autozone tested it as good. Alternator is about 1 year old.

No CLUE what to try next.
 

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Discussion Starter · #2 ·
Forgot to mention, Ebrake was locked solid so she had a friend disable it by gutting that part. The ebrake fuse has been removed to stop it from draining the battery. You could hear it buzzing every few minutes.
The only thing we had done was 4 new tires at a Car-x the next day all these issues. 148K on the car.
 

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So first off, based upon your description of gauges "going to zero" and "won't move without a lot of throttle", I'm assuming your vehicle is going into limp mode as a result of your issues. And of course, when you go into limp mode, you're liable to have all sorts of codes which have nothing to with nothing other than you are in limp mode - disables power steering, power brakes and a whole bunch of other undesirable effects.

Second, control module codes can often be somewhat generic are are often related to some other underlying problem - often simply because the various control modules are communicating with each other, they are "aware" of some issue in the comm and fire off a code. You've already cleaned all the connectors and I assume checked for broken/frayed wires.

If it were me, I would start with the one code you can sink your teeth into and one of the original codes found on the car after first incident - the fuel pressure regulator - P0089 (assuming you had no P0087). If that is whacking out, you're going to have all sorts of trouble. Basically, that module is responsible for maintaining proper fuel pressure and ultimately consistent fuel delivery at your injectors. If there is an issue there, both your transmission and engine control modules will be unhappy. It is pretty easy to get to, easy to inspect and easy to replace. Not sure of the cost of the part, however. Check this video here:

Not sure about the ebrake and/or the ramifications of "gutting the part" or exactly what was gutted during the ebrake exorcism.
 

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Discussion Starter · #4 ·
Would the Fuel Pressure Module cause the 101 codes and the ECM to stop communicating with the TCM? Bus errors?
The engine runs fine but once the TCM loses communication is when it goes nuts. It is easy to replace so worth a try.
 

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Discussion Starter · #5 ·
Tried the module you suggested with no luck. Took it back. The car had two codes this time:
TCM U0073
ECM P0700

Cleared them with my tuner and the car runs fine, until it doesnt. I did wiggle the TCM harness again. Maybe some dielectric grease on all the harness connectors?
 

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An electronics cleaner like DeOxit would be the preferred product to use. Dielectric grease does not clean, only lubes and seals connectors.
 

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Discussion Starter · #7 ·
Getting it scanned today by a mechanic. Problem is it may not act up while he has it so finding what the real issue is will be tough. Might just buy a new ECU and try it.
 

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Discussion Starter · #9 ·
It appears nobody has ever found a real solution to these 13 Malibu issues, so I don't have the luxury to keep towing it home and scanning etc. I just don't know if it's the ECU or Wiring or TCM. Most of the codes refer to can bus or loss of communication. Some forums I have seen people replace the ECU and it fixed it. Can get a programmed to VIN (VATS delete) plug and play one for $275 ish so will try that first. If we didn't still owe on this car, it would be gone.
 

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I would start with the cheap stuff first. I get what you're saying about the control modules, but often I see "loss of communication" and it's not a loss at all - it just doesn't like the communication it's receiving. And again, in the absence of a mechanic who can truly troubleshoot the issue, my personal feeling is start with the cheap stuff. AND you have no code for the high pressure pump, so I feel the control module in your trunk would be a good place to start. I've see the Delco part for about 50 bucks and its an easy swap for vehicle owner. Again, that original code would nag at me until I did something about it.
 

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That battery may be only 4 months old, but one or more connection could be an issue.
 

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Discussion Starter · #12 ·
Replaced the battery with a new DieHard AGM battery. $300. Ran fine for a week or two. Took it in for the toe link recall and was fine. Started it this morning and service stabilitrac and crazy codes again. Of course, we did not have the scanner on it at the time it did it. The new ECU arrived today. Will replace that next. $189. If that doesnt cure it, would I go for the BCM next?
All connectors have been cleaned and dielectric grease added.
 

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Replaced the battery with a new DieHard AGM battery. $300. Ran fine for a week or two. Took it in for the toe link recall and was fine. Started it this morning and service stabilitrac and crazy codes again. Of course, we did not have the scanner on it at the time it did it. The new ECU arrived today. Will replace that next. $189. If that doesnt cure it, would I go for the BCM next?
All connectors have been cleaned and dielectric grease added.
Please check the ground wire that goes under the radiator water hose, and as many as you can and the connectors. I had a problem that had me crazy for 8 days, and it was only to insulate the ground wire and the connector that goes to the computer of the automatic transmission, I have a Malibu 2013 LT, it showed me 8 or 10 error codes, the The main issue was the automatic transmission, I lowered the valve body, washed it, changed the oil, and it kept making errors. And the problem was with the wiring, the earth is roasting with the heat of the radiator hose, I just insulated it and made it go lower and not touch the radiator hose, and the connector to the automatic box had fallen off the insulation You could see the cables that entered the connector, the fault did it to me when the car was warming up, I have not had the fault for 3 weeks, in Mexico you go to a mechanic and he offers you to change the engine and automatic gearbox quickly

In the car menu it tells you the alternator charge should be between 12 to 15, if it is outside these parameters it could be your regulator that is damaging something. Good luck and please let me know if the problem is solved. Greetings from Mexico
 

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Discussion Starter · #15 ·
I have Deoxit cleaner and connection enhancer coming tomorrow. I will clean and treat the ECU and TCM harness connectors. I am going to remove the fuse box and do the same with the main connectors and each fuse one at a time. I will also do this with the ground wires I can find. Any other harness connectors under the hood I need to find? Is there a EBCM connection? Is that the correct term? Electronic brake controller? Do I need to do this to the BCM under the center console? The video I posted above is the EXACT thing that is happening.
 

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Discussion Starter · #16 ·
I have Deoxit cleaner and connection enhancer coming tomorrow. I will clean and treat the ECU and TCM harness connectors. I am going to remove the fuse box and do the same with the main connectors and each fuse one at a time. I will also do this with the ground wires I can find. Any other harness connectors under the hood I need to find? Is there a EBCM connection? Is that the correct term? Electronic brake controller? Do I need to do this to the BCM under the center console? The video I posted above is the EXACT thing that is happening.
I have removed the ECU and TCM harness connections. Getting ready to use Deoxit on them. I did notice the TCM connector isn't all that tight when latched. There is another harness right above the TCM next to the grounds. Don't know what it is but cleaning it as well. Took coolant tank off to get to the EBCM connector but have no clue how to remove it. Tight space and cant figure out if I have to pry on it or what. There is a zip tie on that I removed. Found another harness connector above that on the firewall. Also removed the 3 harness connectors on BCM in center console. Wow that thing is buried. Found two more grounds on the strut assembly (body). Removed entire fuse box to clean all connectors there. I would feel better if I could get the EBCM connector off to clean it but doesnt appear I can without removing all the lines and taking the whole thing out.
 

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Discussion Starter · #17 ·
Put it all back together and I get U0101 and P0700 every time I start the car. Seems to happen every time now.

I noticed the gear indicators are not lit. Then they do light up and when I press on the brake I can feel a click in the shifter. If I put it in drive and the indicator blinks randomly and I can feel that click as well. Is this the TCM or something in the brake pedal? When I shut the car off I can hear several clicks from the transmission next to the TCM connection. Clicks for a few minutes than stops.
 

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U0101 will set P0700 codes. Closely inspect the harness and look for bent pins in the connectors.
|What are the Possible Causes of the Code U0101 Chevrolet?
  • Faulty Transmission Control Module (TCM)
  • TCM harness is open or shorted
  • TCM circuit poor electrical connection
 

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Discussion Starter · #19 ·
I read that the Deoxit can take hours to dry or evaporate. I started it this morning and it works, no codes. I have driven it twice about 40 minutes each time. No codes so far. Wiggled and tugged hard on all the cables while running. No codes it's worked before, do fingers crossed.
 

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It's definitely the Transmission Control Module. It needs replaced. Only comes with all the solenoids too. You can get one used or refurbished for $130-$350. Then you'll need it adapt learned with a mechanic friends scanner or a shop that programs swapped modules.
 
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