Electrical Problem - Help Needed

stangphan

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Long Post Incoming...

I am having a bigtime electrical issue that I am hoping I can get some answers/help with. I have used the search bar and read through countless threads describing similar problems, but nobody seems to know or post the actual fix. The threads all fizzle out. I will be as detailed as I can with what changes I have made and what troubleshooting I have done.

I have a 2005 Mustang GT. I am running AM cat-backs, JLT series 3 intake, and bama tune. I previously had an offroad X-pipe on it, but got tired of the codes from not getting it tuned, so I went back with the stock H-pipe. About 3 months prior to going back to the stock H pipe, my AC stopped working and the car started throwing other codes. It began throwing P0443 (EVAP Circuit) and P0645 (AC Clutch Relay Circuit).

I have checked and confirmed that all of my fuses and relays are good.

I changed the purge valve and no change happened. Then I started to troubleshoot the AC. Sometimes the AC works, but most time it does not. It is not low on freon. I checked for power at the fuse box and was getting all power but the ground that the PCM is supposed to send to engage the AC clutch was not there. I could jump the pins and the compressor would run all day. I then went to the clutch cycling switch and jumped the pins and the compressor would run all day. I changed the cycling switch and have not had the AC code since, but still do not have AC.

The next day I was on the interstate and the car just quit...showed the wrench light, lost power, drove to the off-ramp, and it cut off. I ran the codes and got the following: P2105, P151A, P0645, P0600, P0481, P0480, and P0446. Started it back up and had no problems. The next day I took the fuse box completely apart and crimped down each wire connector in the bottom of the fuse box to ensure there was a good connection. I reset the codes and haven't had that problem since.

Now I am getting codes P0135, P0141, P0155, P0161, and P0443.

I am wondering if I have a PCM problem, my tune screwed it up, or something else...just can't seem to figure it out but the problem seems semi-common. Any help? Will cross-post on a couple other places.
 

hotcobra03

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H30 DTCS P0135 AND P0155, P0141 AND P0161: HO2S HEATER CIRCUIT IS SHORTED TO GROUND, SHORTED TO VPWR OR OPEN CIRCUIT. DTC/HO2S Reference List: DTC P0135 = HO2S HTR-11 DTC P0155 = HO2S HTR-21 DTC P0141 = HO2S HTR-12 DTC P0161 = HO2S HTR-22 DTC P0147 = HO2S HTR-13 DTC P0167 = HO2S HTR-23 If PCM was disconnected during a previous Pinpoint Test, reconnect PCM now. Visually inspect the HO2S circuit for exposed wiring, water contamination, corrosion and proper assembly. Were any concerns found during inspection?
 

stangphan

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0135 AND P0155, P0141 AND P0161: HO2S HEATER CIRCUIT IS SHORTED TO GROUND, SHORTED TO VPWR OR OPEN CIRCUIT. DTC/HO2S Reference List: DTC P0135 = HO2S HTR-11 DTC P0155 = HO2S HTR-21 DTC P0141 = HO2S HTR-12 DTC P0161 = HO2S HTR-22 DTC P0147 = HO2S HTR-13 DTC P0167 = HO2S HTR-23 If PCM was disconnected during a previous Pinpoint Test, reconnect PCM now. Visually inspect the HO2S circuit for exposed wiring, water contamination, corrosion and proper
So go through all of the wires and look for exposed, open, wiring?

I don't believe that the PCM has ever been disconnected.
 

stangphan

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Have you tried removing the tune to see what happens? As in putting stock tune back in.
I have switched the tune back to the 93 race tune from the 87 tune but have not put the stock tune back in. Is it ok to runt the stock tune with the CAI/Exhaust upgrades?
 

2003RedfireVert

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I have switched the tune back to the 93 race tune from the 87 tune but have not put the stock tune back in. Is it ok to runt the stock tune with the CAI/Exhaust upgrades?
Depends. Is the diameter of the Intake tube where tue MAF sits the same size as stock? If so, you can put the stock tune back on. If not, it won’t run right since the MAF curve will be off.

Do you have the stock Air Intake?
 

JaCobro

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^^^what he said.

I’m willing to bet the PCM is crapped out.

But if you are able to put the stock tune back to rule that out. Then check all wiring for anything obvious. Most flow charts for those codes will end up saying replace pcm if all wire/circuit testing is good.
 

stangphan

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Depends. Is the diameter of the Intake tube where tue MAF sits the same size as stock? If so, you can put the stock tune back on. If not, it won’t run right since the MAF curve will be off.

Do you have the stock Air Intake?

^^^what he said.

I’m willing to bet the PCM is crapped out.

But if you are able to put the stock tune back to rule that out. Then check all wiring for anything obvious. Most flow charts for those codes will end up saying replace pcm if all wire/circuit testing is good.
I’m not sure if the diameter is the same size, but I do believe I have the stock one in the attic. You’re suggesting I put it on, flash it back to the stock tune, and see if the problem persists?
 

JaCobro

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I’m not sure if the diameter is the same size, but I do believe I have the stock one in the attic. You’re suggesting I put it on, flash it back to the stock tune, and see if the problem persists?
Correct. Assuming you did not have the same problems before the tune was installed.
 

hotcobra03

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Correct. Assuming you did not have the same problems before the tune was installed.
So go through all of the wires and look for exposed, open, wiring?

I don't believe that the PCM has ever been disconnected.
I'm thinking a fuse blew..you have code for all 4. Blown fuse is a open circuit.

However there may be a wire shorting out from the work you just did on exhaust ,
 

stangphan

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However there may be a wire shorting out from the work you just did on exhaust ,
I’m trying to search for them. The problem was happening before the exhaust Change too though. But I’ve looked at all the wires close by and can’t find any pinched or exposed. I have been reading wiring diagrams tonight and may go purchase a multimeter to troubleshoot.
 

MG0h3

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Def buy a multimeter.

Doubtful that you have a shorted wire. If a power wire shorts to ground, fuse blows.

If a ground shorts to power (very unlikely) fuse blows.

As mentioned, all the 02 codes would have me checking the work around the exhaust. Not sure that would cause a total shutdown though. But you already checked there and didn’t come up with anything.

I suspect the AC issue was isolated and while you fixed the clutch issue, can’t comment on why it isn’t blowing cold.

Confirm that your battery connections and grounds are good before going too far down the rabbit hole.

Buddy at work had intermittent dying that started after he installed an inverter which was wired to the batt terminals. I was able to wiggle the ground terminal off. He would get every light on the dash, then dead. He could randomly get it going again after sitting for a few minutes.

Every now and then someone will have strange problems like this and reloading the tune will fix it.

Make sure the batt terminals and grounds are good first.


Sent from my iPhone using svtperformance.com
 

hotcobra03

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Yes. Fuse 47 in the BJB would be the one to check. But he said all fuses were good.
On line help is tricky.
This gets power with key on
It may have been good before than popped.
Circuit 391 also powers evap controls which he also had code for .

I haven't looked at the other pile of codes yet,

But this Circuit is where all his codes are on now
 

stangphan

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Def buy a multimeter.

Doubtful that you have a shorted wire. If a power wire shorts to ground, fuse blows.

If a ground shorts to power (very unlikely) fuse blows.

As mentioned, all the 02 codes would have me checking the work around the exhaust. Not sure that would cause a total shutdown though. But you already checked there and didn’t come up with anything.

I suspect the AC issue was isolated and while you fixed the clutch issue, can’t comment on why it isn’t blowing cold.

Confirm that your battery connections and grounds are good before going too far down the rabbit hole.

Buddy at work had intermittent dying that started after he installed an inverter which was wired to the batt terminals. I was able to wiggle the ground terminal off. He would get every light on the dash, then dead. He could randomly get it going again after sitting for a few minutes.

Every now and then someone will have strange problems like this and reloading the tune will fix it.

Make sure the batt terminals and grounds are good first.


Sent from my iPhone using svtperformance.com
The AC clutch issue is actually still an issue. All the components are good as far as I can tell, the clutch just doesn't engage when it is supposed to. It will on and off maybe 5% of the time randomly.

My battery terminals are clean and connections are tight...I will check the wires again though. I am going to try to reload a tune this weekend....waiting on my new computer to get the tune downloaded to the tuner.
 

stangphan

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On line help is tricky.
This gets power with key on
It may have been good before than popped.
Circuit 391 also powers evap controls which he also had code for .

I haven't looked at the other pile of codes yet,

But this Circuit is where all his codes are on now
Yeah, I pulled it out and visually checked it, but its sounding like maybe I need to check with multimeter?? I have been trying to search for a problem with that circuit, but could not find one. I pulled the PCM yesterday and cleaned all of the terminals, but nothing changed and they didn't look corroded or anything. The car only has 49k miles on it, so it's not like the wiring should be in too bad of shape outside of the age of the car.
 

stangphan

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^^^what he said.

I’m willing to bet the PCM is crapped out.

But if you are able to put the stock tune back to rule that out. Then check all wiring for anything obvious. Most flow charts for those codes will end up saying replace pcm if all wire/circuit testing is good.
The more I troubleshoot, the more I'm beginning to believe you are right about the PCM. I am going to check the interior unit/fuse box next as I have had the firewall drain/leak problem; however, it sounds like that is not the issue as most people have issue with other electronics when that is the problem.
 

JaCobro

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You’re on the right track. It’s a process of elimination. Which can be frustrating sometimes with possible wiring issues. Double check power, grounds, and continuity in problem systems/circuits. If all good try reflashing tune before condemning pcm.
 

hotcobra03

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Yeah, I pulled it out and visually checked it, but its sounding like maybe I need to check with multimeter?? I have been trying to search for a problem with that circuit, but could not find one. I pulled the PCM yesterday and cleaned all of the terminals, but nothing changed and they didn't look corroded or anything. The car only has 49k miles on it, so it's not like the wiring should be in too bad of shape outside of the age of the car.

The pcm relay#1 when triggered powers f1-47


If fuse in hand is good looking may still be blown,,
A test light/ multi meter will tell if the fuse is even getting power,

Both evap sensors you have code for ,
Ac clutch code,
All 02 codes ..


Also what are you using for wiring diagram?

The ford factory manual is what I use ,,it has the answers for us.
It also has section on hvac testing.

That FYI free browsable manual link works ok but isn't complete in pc/ed section for codes.
 

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