Pcm

[NASFD35]

I think I have a problem with my PCM. The service engine soon light came on and it’s giving me a MAP sensor code. I replaced the sensor and it’s still giving me the same code. Today the low coolant light came on and the reservoir is full. I have a leak in my windshield in the passenger’s side and water is running down the inside of the firewall. Will this “short-out” the PCM? And, where can I buy another PCM? I’ve googled the part, but I’m unable to find one.

[Hubert]

Update your signature so we know details of truck. I don't know much about replacing them but later years the anti theft might have some nuances to work out???

You could go to junk yard and get one from a similar truck. Or buy an aftermarket one that is reprogrammed like Kennedy or Heath.

Water and electricity cause a lot of corrosion to terminals etc so get the windshield fixed. I am one to talk mine leaks too. Seriously it causes some kind of accelerated electrolysis and really causes lots of issues.

I heard if a car gets flooded the insurance will total instead of fixing it due to all the little things potentially bad like air bags sensors etc etc. One adjuster said it it clicks and tries to start they may repair but if nothing happens with key on they total it (regardless of miles condition etc).

[JohnC]

What is the code?

I'm pretty sure the coolant level sensor is independent of the PCM.

PCM failures are rare.

[NASFD35]

John, I don't remember the code it gave us, it was a few weeks ago when I had it plugged in.
The MAP sensor was the first thing to show up, then today during a heavy rainfall the low coolant light came on after a bunch of water came in......seemed like the likely cause....

[sailun]

I always had a leak there too. It wasn't the windshield.

Fixed it by removing the black plastic cowl trim, cleaning out leaves and debris, and sealing the mounting holes with RTV.

Also look at the body joints in that area, and clean out any area where water is supposed to drain out.

Electrical issues.

While you are in the area, the connector from the ECM to the engine compartment is directly below the A/C on the firewall. Seems likely that it gets dripped on from the A/C, and splashed from the road. Mine was pretty filthy. Cleaned gently.

Also, there was a stick-on piece of heat shield material covering the connector, I tried to put it back in place. I doubt it's still there.

Clean, check or replace all grounds, especially from ECM to rear of intake manifold, body to frame, engine to frame. There's quite a few threads for what to clean/replace, and add. Search the site for grounds, and ECM B fuse. My truck was blowing the ECM B fuse due to the bad ground.

You might want to just wiggle or disconnect/reconnect the plugs on the ECM. You never know, can't hurt.

[jerry598]

John, I don't remember the code it gave us, it was a few weeks ago when I had it plugged in.
The MAP sensor was the first thing to show up, then today during a heavy rainfall the low coolant light came on after a bunch of water came in......seemed like the likely cause....

Still need to know what truck you have before we can provide any good advice - except, John's right that PCM failures are rare. Years ago my truck was in for repair at the dealership and they decided it had a bad PCM. I had just replaced it a month earlier as part of troubleshooting a number of issues. So, we pulled it again and got another new one under warranty. This 2nd replacement did not fix the problem either - the dealer was wrong.

[Robyn]

I am very suspect that you have a connector issue somewhere. Could be the through the firewall connector as mentioned or at the ECM/PCM itself.

Yank the glove box out and have a peek at the computer and see if water is getting onto any of the connections.

Unhook the batteries and then unplug the computer, spray all the connectors with contact cleaner and reinstall.

If you live in an area that uses salt any and all connectors that are outside the cabin can be suspect.

Inspect the though hull fitting right below the heater to make sure there is not issues.

The Low coolant sensor IIRC is a separate system and does not feed through the ECM.
This system has a module that senses the presense of liquid and either turns the light on or off depending.

BUT the wires and connection could come through the feed under the heater area.


Robyn

[sailun]

Just remembered, that every year when it got cold, my coolant sensor light would come on, even though coolant level hadn't changed.

I would put in about 2 tablespoons of coolant, and I would be good for another year.

Just a ritual, I guess.

I bet you it only happens the first start of the day, when it's cold, right ?

[NASFD35]

Jerry…sorry. I have a 1995 K1500 with a 6.5L TD.
Rodyn….. I’ll check all of that the next dry day we get.
Sailun……I’ll clean/check all of the grounds again. Also, the low coolant light has been on constant for 3 days now.

[THEFERMANATOR]

Need to know the code first, and the PCM has zero control over the low coolant light on a 95. There is a module over on the passenger side behind the kick panel for the low coolant light. I would check the grounds over behind the passenger kick panel as you said water has gotten down there and it may be causing it.

[NASFD35]

Ok, I finally had the codes checked. The current code is a 31. The codes in history are 16, 31, 93, 94, and 96. Again, this is on a 95 6.5L TD.

[NASFD35]

So……with all of the codes issues I took my truck to the shop. Mechanic there couldn’t nail down anything definitively as the source of the problem. One of the other things noted on the computer (other than the codes) is; The ODB was showing the truck in 4 high when the transfer case was in 2wd. Move the lever to 4 high and the computer was showing 4 low. Some of the other things noted are; there is a horrible knocking noise coming from the engine (very similar to the fella from the other thread), the truck drops speed as soon as you take your foot off of the pedal, it has trouble maintaining speed in cruise control, and there feels like there’s a miss that starts around 60 mph.
Something I found out from the shop was that the truck has a performance chip in the computer. Could this be the source of the problems? Is there anything special I have to do when I take the chip out? Do I need a stock chip to replace it, and where can I find one?

[THEFERMANATOR]

http://www.kennedydiesel.com/readcodes.html

DTC 16 - Vehicle Speed Sensor Buffer Fault
DTC 31 - EGR Control Pressure/Baro Sensor Circuit Low (High Vacuum)
DTC 93 - #3 Cylinder Balance Fault
DTC 94 - #4 Cylinder Balance Fault
DTC 96 - #6 Cylinder Balance Fault

With all of these codes I would clear them and see which ones come back first. There is a chance that your EGR valve is stuck wide open and causing many of your running issues though. Stock chips can be had from the dealership for about $60, but I would reccomend upgrading to an F engine prom chip[ and disabling the EGR system if it were mine. I've got an ECM and PROM chip from my 95 BURB I was looking to get rid of if you're interested.

[NASFD35]

I was kinda leaning towards a vacuum or EGR issue, so all if that make sense. Is there a way to test the EGR? The truck seems to run fine for a little while after I disconnect one of the vacuum hoses, but then it gradually gets worse.
My neighbor has the same engine in a 3500. After reading some info, my understanding is that the 6.5 TD has been “modified” to reduce some power…..I think this was accomplished through the EGR. By “F” engine prom chip and disabling the EGR system, are you talking about boosting the “engine horsepower”? How much work/time is involved in changing all of the stuff?