Limp mode, DTC U0107 and alarm issue

FR33SPIRIT

MEMBER
2005 ACURA TSX
2.4L
4 CYL
2WD
AUTOMATIC
170,000 MILES

Purchased the car listed above. Original owner had Audiovox passive alarm put in. I only drove the car a few minutes before letting my brother drive it for 4 years. He stopped driving it and it sat in his yard from 2015 or 2016 until this year because he didn't want to pay for maintenance, tires and a power steering rack. Earlier this year I had some maintenance done, put a new battery and tires and took it in for recall on PCM where they put a thin piece of plastic over it (recall said PCMs could get corrosion from wet carpet). I drove it less than a minute when all of a sudden it went into limp mode, lost communication with TAC module. I followed service manual flow chart for the dtc u0107 and all the wiring was normal (correct voltages and continuity) it brought me to a step saying to swap the TAC module with a known good one so I got one and it didn't help. I forgot to mention that my brother had the aftermarket alarm either disabled or the wires cut or something but it hadn't been arming in years. The day after the limp mode happened I drove half a mile to the store and when I went to get in the car the alarm went off and has been passively arming ever since even with the doors and hood open. It the alarm was not doing this the night before when it went into limp mode tho! Lol. Yea another thing is even before all this started the car stopped coming out of park, so I've had to put the key in the manual override hole near the gear selector n put it in neutral before cranking. I'm totally at a loss for what could be causing this and can't afford to pay a professional to look at it. Is the alarm module connected to the PCM in any way? I'm curious because where I'm at now is thinking it is a faulty PCM but would really appreciate any input. Thanks!

5 Replies

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

I've attached step-by-step instructions for that code for your vehicle.Here is a tutorial showing how to check wiring as well:

https://www.2carpros.com/articles/how-to-check-wiring

Hope this helps and thanks for using 2CarPros.
Danny-

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Saturday, October 5th, 2019 AT 6:36 PM

FR33SPIRIT

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3 POSTS

Thank you for taking the time to post all that. However this is the service manual steps I was referring to when I said I had went thru the flow chart for my particular DTC. Actually rather than just going thru and going to the step it says go to the 2nd, 3rd 4th times I've repeated these checks I did every single step with all of them leading me to either change the TAC module or the PCM! If it weren't for the aftermarket alarm acting crazy now I'd def think the prob had to be the PCM but I'm not sure since I don't really know how the PCM would affect the alarm. Is there anything else you can think of that would help me make sure the PCM is bad or to diagnose the real problem here?

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Saturday, October 5th, 2019 AT 6:57 PM

DANNY L

MECHANIC
5,648 POSTS

Hello again.

So, Is the aftermarket Audiovox alarm completely disconnected? Can you upload photos of where the wiring was spliced in? Take pictures with your cell phone and you can upload here.
Danny-

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Saturday, October 5th, 2019 AT 11:51 PM

FR33SPIRIT

MEMBER
3 POSTS

Let's try this again. What I write keeps getting deleted before I can post! Ergh! So aggravating! This time I am going to copy it to clipboard so it should be the last time ill have to type.
Okay, so the alarm isn't an issue now.I found the paperwork that goes with it and changed the settings to put it back in active mode. It got into passive mode somehow. Oh and the wires I thought were "open" were just for optional accessories like remote start.

I'm going to paste something I saved in my notes that I wrote on another site so I can save time. Some stuff might be redundant from what I've already written here so I apologize in advance:

hoping you guys can help me figure out an issue I'm having with my 2005 Acura TSX. It's in limp mode with DTC U0107 (lost communication with TAC module).I've done the testing in the service manual and everything checks out as normal.(Continuity, voltages at TAC module, TAC module relay & PCM) the only thing that I'm unsure of is the test that has me probing the TAC module B+ circuit(with harness unhooked). It says to turn the ignition on and check voltage. Then it asks whether there is battery voltage for about 2 seconds. Well in my case there is battery voltage as long as the ignition is on! (Longer than 2 seconds)
I've already replaced the TAC module. Oh and another thing that doesn't seem right is. One of the service manual tests says to look inside the throttle body and check the throttle valve operation. Hold the accelerator pedal to WOT then turn on ignition. Then it asks "does "it"-(and yes the wording says "it") open after the throttle valve closes? (The only thing that it seems it could be referring to is the throttle valve/plate). But in my case the throttle opens once and closes and will not open again.

One other thing that may be worth noting is that occasionally I'm unable to get the car out of park without pressing the manual override button beside the gear selector. It's almost like the brake pedal won't push down quite far enough when this happens. The U0107 code is not intermittent however. These 2 issues may be unrelated but I figured it was worth noting.

Here's a few other details that may or may not be important. My obd2 diagnostic scanner shows 0% for throttle position and relative throttle position. My car had a recall for corrosion on PCM & they were supposed to have added a plastic cover that bolted down WITH the PCM but upon removing the trim & seeing the PCM I noticed the cover was not bolted so they did not remove the PCM bolts before adding the cover. Also the PCM is heavily corroded on the drivers side. I'm thinking that the problem is the PCM even tho the pins and wiring harnesses aren't corroded (they're on passenger side) I'm thinking there may be corrosion on the PCB. I haven't been abl2 remove the PCM to inspect bc I can't get the bolts to loosen. I just really want to make sure it's the PCM rather than assuming, replacing it & still having the problem!
Any input is greatly appreciated!
Thanks, Heather Hodge

The steps I am referring to are #8-10 in the images you sent above and step 20. When going thru the flow chart and going to the steps it says to go to it actually leads me to replacing the PCM first so I guess I should just go with the obvious but I just want to make absolutely sure the PCM is to blame. It seems like the only way to do that is by process of elimination, so is there anything else you can think of that I could check before condemning the PCM?

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Wednesday, February 12th, 2020 AT 8:45 AM

KASEKENNY

MECHANIC
18,907 POSTS

Yeah. Clearly without going through all the steps with you, that looks pretty clear that the PCM needs replaced.

However, if there was a recall to prevent the PCM from corroding then they should replace the PCM under the recall even though they installed the part to prevent it. Clearly it didn't prevent it.

This type of corrosion is typical on control modules. It is a clear sign there is water intrusion and I would be surprised if they don't cover it. In fact if the dealer doesn't cover it, I would call the OEM to get them to make the decision on whether that should be covered because the dealer isn't the one recalling the component, the OEM is. Plus they may just look and see the recall is complete and tell you that they can't cover it. This is not true. The dealer can redo the recall and replace the PCM if it meets the stated failure in the recall even if it had been completed prior.

The only issue may be if they try to say that the corrosion didn't cause the failure. This would be a hard sell for me.

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