Hi,

I had my old PCM replaced as my '99 PSD had stopped running, and even with the new (rebuilt) pcm, it still will not start. It is throwing a PO605 code which after searching this forum I found it is a normal code. My mechanic said there is power getting to it, but nothing coming out, just like the old one.

The new PCM came from a reliable source.

Any ideas?

Thank You

 

Unplug your Diablo tuner and try that. You have checked the fuses I assume?

 

Dangit man.....that is an awful expensive place to start.

Give us more history/info.....

 

Are you getting a WTS light?...

 

X2. Also check fuses and relays.

Then where exactly is the power coming in at, and where is it not coming out at? Lots of wires coming off the PCM.

I also like the idea of removing any chip/tuner to rule that out.

 

My mechanic has checked the fuses and relays. Aside from the PO605 code, it is also throwing an air intake, no back pressure codes (due to mods), and a no test replace PCM code. He has a call into a Texan company that deals with this unit, but has not heard back from them yet. The Diablo is not plugged in. I did not want to say this yet, and I am not assigning any blame, but the PCM is a DP Tuner that I just purchase. Jody is on vacation this week, so was not able to contact him.

What is a WTS light?

Here is a little history:

I took the truck into the shop back in January because it would go into "limp mode" and check engine light would come on. We thought it could be the PCM, but found it was a jack that is mounted on the valve cover that had shorted out and he replaced it. My mechanic said that it was a weak point in the engine and that it can take out the PCM. It ran fine for a few weeks after that until I took the truck back for front end suspension work. When I picked it up, I drove it for less than a mile, when it went back into limp mode and check engine light came back on. I turned around and took it back. My mechanic took a code reading, wiggled some wires on the right hand side of the engine compartment, and told me it should be fine for a little while and to bring it back in so that he could check it out when I could leave it with him. It ran fine for about 400-500 mi. than stopped running and I had to have it towed in. He recommended getting a new PCM and the DP Tuner was one of the best ways to go.

 

Well Jody can sell a bad PCM just like anyone else. Stuff like that happens every once in a while. That being said, and after listening to more of your story, I don't think the PCM is, or ever was your problem.

I guess the first question is, how much is your mechanic charging you? For about $340 you can buy your own scanner and figure this stuff out on your own. Next, let's go through what the mechanic has done. The loose jack mounted on the valve cover is what we call the UVCH (under valve cover harness) when it comes loose, it looks like this



When this happens 1 - 4 injectors quit working and the truck will run rough, shake, and generally make you think it's about to explode. Your mechanic is right about this being a know issue on these trucks. The fixes for this involve either 1) an updated harness, 2) a shim kit sold by Ford/IH, or 3) a DIY shim to keep the connector plugged in. Which method did your mechanic use to repair it, or did he just plug it back in? Did he do one side or both?

Next, many people have had this happen and no one has had to replace their PCM because of it. There could be an issue with your Diablo causing a PCM issue, but that is unrelated to the UVCH connector. If anything were to fail due to UVCH issues, I would be looking at the IDM (injector driver module) before suspecting the PCM, since it's wired between the PCM and the injectors. It sounds like your mechanic saw the P0605 code (which the book says is a bad PCM) and just said it needs to be replaced.

If we back up and start looking at this from a fresh perspective, does the WTS (wait to start or glow plug light) come on for a few seconds when the key is first turned on? Does it go off after a few seconds? Your comment about the mechanic wiggling wires around the drivers side makes it sound like he suspected (or was grasping at straws) the wiring at the 42 pin connector. This is another known issue with the 7.3 If you look below the air intake tube going to the turbo, you'll see a square box with a bolt going through the middle of it on the drivers side valve cover. The wires below, or behind this box have been known to rub against the metal and chafe. If this happens, it can cause a short to ground which will reset or disable the PCM.

As for the recent suspension work, also check for a wiring harness over the drivers side front shock since those wires can have the same issue.

Anyway, when you turn the key on, do you hear the fuel pump buzzing? Is the fuel bowl full of fuel? Is the HPOP reservoir full? Does the tach bounce while cranking? Is there any smoke out the tail pipe while cranking? Have you been keeping the batteries on a charger? (If voltage drops too low while cranking, the IDM will not enable the injectors).

 

I know this is going to be really far fetched, but just hear me out.

I have had the same exact problem minus the non-starting, I had a strange "moving" "intermittent" misfire on a V10. I get no power to the OBD plug and all wiring and fuses are good. I brought it to a mechanic and he spliced a hot wire to the plug and got power that way but the computer would not respond so I removed all his "mess of crap" troubleshooting. After much more troubleshooting and a long weekend trying to figure out what was wrong with the truck, I got frustrated and punched the horn. When I did that, I got power to my scanner for a moment and then it went away. I then started gently slapping the dash in different places until I got power to the plug again. The area was just to the left of the steering wheel below the headlight switch.

I pulled the dash apart to find the gem module and if i tapped it the power would come on. I can hear something loose in the GEM if I shake it. so I found one in a junkyard and replaced it. Problem solved.

 

Actually my mechanic is a friend of our family and grew up as friends with my younger brothers. Also, one of my brothers helps him out at the shop all the time, and does much of the labor under his supervision for which I am not charged for. So, I get things done quite reasonably.

I will print out the posts here and take it to him tomorrow.

Thanks for all the info!!

 

Well if that's the case, have him monitor ICP psi, IPR duty cycle %, fuel pulse width and vehilce power while cranking and tell us what those numbers are. That is after you tell us about the WTS light, check the fuses & relays, tach bouncing, smoke, and verify fluid level in the fuel bowl and HPOP reservoir.

 

Chris is offering up valuable suggestions here. You should heed them.

 

I am leaning towards Chris' suggestion of a short over the shock tower. He has been there done that, and the fact that you stated that thers was some front suspension work done, the wiring harness may have gotten moved back over the shock tower, and may be shorting out. If so, then liquid electrical tape is your new friend, of course follwed by a good wrapping of regular electrical tape, and some convoluted wire loom.

 

I agree with you 100%.
You must of missed my above post where I wrote that I will print out all the responses and give them to my mech.

 

Here is the latest with my PCM problem. The DP Tuner PCM was installed and truck still will not start. There is power going out to everything except the IDM. The PCM is throwing a P0605 code, and Jody told my mechanic that is programed into all his PCM's, and does not think it is a bad new PCM.

So, what do I do next? Replace the IDM?

Thanks for any help.

 

I still don't think it is, or ever was your PCM. Did you check all the suggestions we gave you? Where exactly are you taking a reading to determine there is no power going to the IDM?