Mustang idle issues, KAM memory fault

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NothingButMustangs
Posts: 4
Joined: Mon Aug 27, 2018 7:18 pm
Vehicle: Ford Mustang, Cobra, 32vDOHC, 2003

Mustang idle issues, KAM memory fault

Post by NothingButMustangs » Tue Aug 28, 2018 10:40 pm

I have a 03 Mustang Mach 1 (75k miles). I have had idle issues which I have been working through. I recently installed forscan and one thing that stands out is that it shows the KAM memory has a fault (so I assume bad fuse and nothing to power the kam). This make sense to me as I think every time I start the car it has a very high start (around 2k and then drops) almost like on cold days or when the KAM was reset.

Problem is I don't know which fuse to check. I checked every fuse on the power distribution block and the fuses inside the car under the left of the driver seat, all good except cigar lighter (which I replaced today). Anyone know exactly what to check?

Also what is the normal voltage to the pcm. It is showing around 13.2 to 13.6. I was expecting a relatively consistent 12 volts.

Thanks in advance.

sheltonfilms
Posts: 76
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Vehicle: 2000 Ford Ranger 2.5L Gas USA / 2013 Explorer LMT
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Re: Mustang idle issues, KAM memory fault

Post by sheltonfilms » Wed Aug 29, 2018 12:33 am

F2.21 is the fuse that is "Hot at all times" for the PCM. It's 5 amps and is in the Central Junction Box.

If this fuse is good make sure there is power to it.

If all this checks out then go to the PCM connector and check for voltage on pin 55 (Red wire with white stripe).

It's straight battery voltage which means it will show 13+ volts when the vehicle is on (alternator charging).

NothingButMustangs
Posts: 4
Joined: Mon Aug 27, 2018 7:18 pm
Vehicle: Ford Mustang, Cobra, 32vDOHC, 2003

Re: Mustang idle issues, KAM memory fault

Post by NothingButMustangs » Wed Aug 29, 2018 7:42 pm

Thanks so much!!! I checked F2.21 on the inside drivers panel and it has battery voltage in and out, fuse is good.

So I am now over on the passenger side taking checking out the computer.

Question, can I probe that wire pin 55 while the harness is off the PCM (I have the battery disconnected taking out the pcm, but wanted to plug that back in and check for that voltage with pcm disconnected (vs. a backprobe on the pcm).

Thanks.

NothingButMustangs
Posts: 4
Joined: Mon Aug 27, 2018 7:18 pm
Vehicle: Ford Mustang, Cobra, 32vDOHC, 2003

Re: Mustang idle issues, KAM memory fault

Post by NothingButMustangs » Thu Aug 30, 2018 5:25 am

OK, I was able to test pin 55 (red with white stripe) on the pcm connection harness (front and back probe), but disconnected from the pcm (this is with engine off key out). It was right about battery voltage (12.34 volts). So I would say that wire is good all the way to the pcm.

I am cleaning the pcm ground and will do some tests tomorrow at the tps and iac (since I am getting some erratic idle off and on). But if the kam circuit still shows fault after another running test with forscan, seems like this is pointing to a bad pcm. Not sure what else impacts no kam power. It there other tests I should do before thinking of replacing the pcm.

Also thanks for the info. It was spot on with regard to the fuses and harness.

NothingButMustangs
Posts: 4
Joined: Mon Aug 27, 2018 7:18 pm
Vehicle: Ford Mustang, Cobra, 32vDOHC, 2003

Re: Mustang idle issues, KAM memory fault

Post by NothingButMustangs » Fri Aug 31, 2018 1:25 am

:cry: :cry: :cry: OK. I ran the latest forscan on my 03 cobra, the issue with KAM was on my 03 Mach 1 which is having idle issues. I did this as a baseline to check forscan is giving me the correct info. And :cry: my cobra shows KAM memory in fault as well. This is simply not possible. There is no issues with that car and both cars can't have that as a common concern. I just don't buy it.

So after 2 days of learning and chasing that KAM wiring, I think it was a red herring.

So I suggest this is a bug for 03 Mustangs in the latest version of forscan. Is there a place to file this as a bug? Or.... could fault mean it is in a learning mode (since I reset the KAM with battery discharge?). I am doubting that.


What I have found is that my 03 Mach 1 has the TPS Mode hanging in PT (part throttle). When it shows this, the IAC is up some and the timing is well advanced. So I think somehow my car is sticking in PT and that must be related to the TPS, wiring to the TPS, or the computer/computer mapping.

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