I am working on a 2003 7.3L w/manual transmission for a friend. It starts if you pull it for 5 miles or so and then it will run.

I told him bring it to me and I would look into it as I have a good bit of experience dealing with this era of powerstroke, but this one has me really frustrated.

I can't get get the DLC to communicate with the PCM properly. Starting out, I made sure all the fuses were good - found several with wire wound around the posts bypassing the fuse protection. Removed all that junk.

Made sure the DLC had power, (cigarette lighter works) etc. There was NO communication with the computer, dead as a nail. The scan tool just kept saying to make sure the key was on. Wouldn't discover modules or anything. Pulled the PCM, sent it off to a company in Illinois that repairs PCMs/ECMs and what not, they said the computer was bad and non-repairable. They are mailing it back for the cost of shipping.

Put in a different ECM from a running donor vehicle, now the DLC acknowledges that other modules exist (ABS and whatnot), but will not read any engine data.

Now, the donor ECM was from an auto transmission, and I know they are flashed differently, but shouldn't I be able to get at least some form of communication with the engine?

I know my scanner works, because it works on other trucks, but on this truck it wont do diddly.

Are there any pins I can check voltage on, etc to make sure the relevant portion of the PCM is getting power to work?

Any thoughts? I found some scary things done in the fuse panel, but since reversing them and replacing with proper fuses I have not had any new ones blow, so if there were shorts, I would expect them to re-blow.

The truck WILL run if pulled for an inordinate amount of time, so that suggests there is life in there somewhere, but I can't get on to the finer points of troubleshooting the engine because I cant get a scan tool to acknowledge the engine exists.

I now defer to guru's of FTE in the hopes they can suggest something I am missing.

 

I am trying to sort this out.


Without a functioning CORRECT PCM, it will be difficult at best to find an end to your quandary.

Are you saying the Truck is being pulled by another, down the road? That's a testing method I am not familiar with.

This is not the end of the world. I presume the wiring anomalies are all connected by a PO or someone who thought they were a electrical technician.

A break out box would allow you to read the values and convert to real world ie: 2.14 VDC = 170*F and so on.

Pin # 43 is the (OG/LG) as the Data Link Connector (OG). My guess is there is an issue between the two. This will allow your Scantool to receive the data.


But, you need a functioning CORRECT PCM for this to be of any help.

Is there a Chip?

Is it a Stock PCM (you will have to open and inspect the board for the part / brand number)? And, again, if you can't read it, you can't confirm the Flash, Tune, Etc.

The PCM Information Label is all you will need to secure another one. There are places that specialize in ford PCM's and can repair them 99.9% of the time.

No. It shouldn't do anything, in theory.

It's "Looking for Love in all the Wrong Places" as well as Sensors that don't exist in the circuitry on an Automatic.

I'm not certain IDM Sync would be achieved either.

Where to from here eh?


I would say your next move is to get wiring diagrams and sort things out. Or, at least ensure the wiring there is correct and get another PCM to complete trouble shooting.

 

An automatic PCM will work JUST FINE to start, run, and drive the vehicle. Don't let anyone tell you otherwise.....especially someone who makes a remark about your "testing method" and who in one breath says that you have to take the PCM apart to look at the board number and in the next that the sticker on the connector is all you need. The PCM board will tell you nothing. A PCM from a 99.5 to 03 manual or automatic will work fine for starting diagnostic purposes.

 

I take no offense to any assumptions about my testing method, without the whole picture, that would seem out of line with proper diagnosis methods, i agree. That being said, I didn't actually test it that way.

The owner of the vehicle, who does not posses a scan tool and lacks other diagnostic tools was pull starting it because in the beginning the starter was bad - I did leave that bit out. The starter was the first thing I fixed. When looking at things in their totality, the person who first started the work (not its present owner) probably burned up the starter from excessive cranking. The present owner actually drove it over to my place and it pulled in running, albeit a bit rough, but running nonetheless.

I have heard differing opinions about the difference between the PCMs and while i acknowledge there are definite differences such as the clutch switch inputs and what not, I was looking for basic engine sensor outputs so i could verify ICP sensor data and so on. I was also hoping to verify that the ECM was receiving any info at all from the motor.

As far as I know, the PCM I put in is untuned.

So, my next question would be this, would a bricked IDM show as a total communication failure, or would the PCM show an IDM P-code?

 

The IDM (PCM) would provide a P Code at minimum if it were faulty. The PCM would see this as missing and log a 1316 (I think). Sync issues can also stem from an incompatible CMP Waveform to achieve activation of the Injector Module Circuit.


As for the PCM, the M/T causes the engine to use several different sensors to provide both fuel and feedback the A/T does not. An example is Water Temperature which is not monitored by the A/T and a few others. Whether or not you could retrieve information is up in the air. I have not attempted it.

 

Did it work on other 7.3s? These are kinda far out there on the autism spectrum ya know.

If the truck runs sometimes, then I'd think the PCM is fine. The PCM will detect a bad IDM and throw a code, often the P1316.

Codes are nice, but I think people rely on them too much. Symptoms and observation will get ya there. From what I gather from the symptoms I'd be looking at the ICP sensor. Is there oil at the connector? Is it original? Also chafing of wires on the harness where it goes across the driver side valve cover? And the CEL is lit, right?

 

[QUOTE=SMT_FORD;16159334]The IDM (PCM) [/QUOTE ] Not the same thing at all.


Without you being privy to what the PCM sees or uses, your answer makes sense as you're left to the will of Ford to tell you these things in their manuals. However, short of a manual transmission PCM being physically short of the hardware to control shift solenoids, everything else will function to a normal standard - to be able to diagnose a no-start issue.......without issue.

I have done it MANY times

 

[QUOTE=cleatus12r;16159720]

Well, your a God. And showed yourself here on the day of resurrection. Please impart your knowledge upon the OP so he can get his truck fixed. Please.

 

All I can do is guess, just like you. I will not, however, send someone on a wild goose chase spending more money than they have to just to chase an issue that isn't related to the test part.