Sounds like you need a break out box from the pcm. I have never used one but might be worth paying someone else if you have any good techs in the area. You need to figure out no communication with the pcm first.

 

New IDM did nothing. So back tracing wires. Read the thread on dieelectric grease. So cleaning all that off too. I used a lot of it on the top of the motor harness, no were else, so cleaning it out. Communincation with the pcm is the least of my issues. Its the result of whats wrong, not whats wrong. Also there is no way to fix that without fixing what ever is wrong. I've checked every connection and wire on the communication side, and nothing wrong. So its a result of the problem, not the problem itself. Ive decided to pull the entire harness from the fuse box to the injectors and lay it on the ground and take it all apart and check wires and for kinks and burns what ever. I have found nothing wrong so far, tested about half the system so far. Most of which have nothing to do with my issue, but checking them all.

 

Before going to that level of desperation, try a new ignition switch. Ideally without any car alarm splicing.

 

Ok, Ill try that. Although all those wires have been tested live and individually on there own, and key on all the lines are sending power throughout. Only thing I see wrong with that system is the key itself and the shifter. I found out in my testing that my shifter was not getting first gear because the two bolts under the dash were practically falling out. Tightened those up and now it shifts fine, but the shifter is still alittle loose because the rubber bushings are shot. I have to lift it slightly to get the key out. Doesn't seem to be related as moving it does nothing to help but I do see it has a pin the moves the mechanism inside the white key block probably making the appropriate connections as you shift. So it could be loose, although again doesn't seem to affect electrical anywhere. The key itself is worn and I can stick it in and wiggle it without turning and it will activate some of the chimes other than the key in chime. So loose but I don't want to re key with a new tumbler. I wanted to remove the alarm, but I'm still trying to figure out the wiring as it has cut the yellows out of the key box, and run through the alarm. So I'm not sure which yellow go to which yellows yet. Still tracing. Only reason I'm trying to remove the alarm is because of a couple suggestions. It is functioning correctly, and does not immobilize the engine, only the starter. The start still works fine, so the alarm is shutting off. But as with my old edge system, these can cause gremlins, so I want to remove it. But again. All its connected to is the key power, and the lights and door locks, and the starter relay. Not sure how it can stop PCM functions, but I am trying to remove it. The future shop guy tapped all the lines about an inch from the key block too. So not much room for repairs. He soldered too, so have to cut. Wish I had the Compu Star drawing for the alarm. But its a few years old now. They didn't even have one. LOL

 

Here's something interesting I'm wondering if I can try. Before sending out, I opened up the PCM to see if there is any burn up in side that's obvious. None there, but I noticed there is a black plug on the bottom or back of the pcm. Inside there the board has an extension with what looks like the programmers/ or probably Ford robot pcm builder, uses this to data link to the pcm. Probably for the machine to do the initial programming. Wondering if I can bypass the wire system and try to data link to that connection???? Any body know of this, and do you know what the pin diagram is for that port??? Hoping to maybe get a code or something out of it. Jody might find codes too, we'll see. Just wondering if this is possible.

 

That is a Programming Connection of which I am not familiar. All the programming I have done has been through J-2534 pass thru tool .

 

I don't mean to be a jerk but you don't know how to troubleshoot this...

 

Duh! No Kidding. Said about a 100 posts ago I havn't got a clue how to find this problem. Apparently neither does anyone else. Got a lot of helpful drawings but little to know help. If I could afford 120 bucks an hour for a mechanic to spend months finding it, then I would. Reason I'm here is to get help. Not get cut up by a guy who obviously has no clue as well. Since your of no help knowing nothing, don't waste everyones time.

 

Thanks for your help. This year truck has no fuses under the hood other than the inline ones. They are all in the fuse box in the cab. That said all the fuses are good and the terminals checked, and even a new fuse box installed with new fuses and relays. The whole reason this is difficult is because nothing is coming back broken. Everything everyone has suggested is working, or should be. What ever broke is real small and hard to find.

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Mods note: Quoted post removed. Quote from a spammer, not a real user

 

I understand you don't mean to be mean or a jerk, but isn't that the whole point of this forum? To help people?

Alex "Quick444" was in over his head after he blew his engine in Alaska. With FTE's help, he swapped in a replacement engine while it was on the side of the road over the course of 5 months.

https://www.ford-trucks.com/forums/9...ml#post8514855

If everyone who was here knew how to troubleshoot their problems, this forum would be a lot less active.

Stewart

 

There is a lot of information ( necessary an un) in this thread to the point I am not even sure what the current issue is, other than the truck will crank but not start. From your first post you have no communications with PCM, fuel pump is not coming on, WTS comes on and stays on? oil can illuminates and stays on....no SES?

One thing I have not seen mentioned ( but I may have missed it) is that if a sensor (MAP,ICP or CPS (CAMP) sensor fail in a high impedance manner they can pull Vref (5v) in the PCM down to the point that it does not function. You can unplug all these sensors and see if the PCM behaves normally and boots up giving you communications with a scan tool.

 

You're right and I shouldn't of put it like that. Throwing parts at it can get expensive.

 

"clem1226": WOW! EXCELLENT POINT!!!! WELL DONE !!!!

Here is an excerpt from a manual....

Testing the 5v Reference Circuit:

• You must have a good wiring diagram and identify what sensors share this reference. All potentiometers, pressure sensors and some hall effects
(cam, crank, vehicle speed sensors) must be isolated to find the short.

• While measuring reference voltage with the key on, (usually at the TPS or MAP because of easy access) start unplugging the sensors one at a time. Find the sensor that causes the reference voltage to return to 5v when you unplug it.

• If you still have no 5v ref. with the sensors all unplugged, then you must disconnect the PCM and measure for a short to ground on the reference circuit. (sensors still unplugged)

• No short to ground then you have a PCM problem. Make sure you check all PCM powers and grounds before replacing the PCM.

 

I suggested earlier in this thread that it may be worth it to take it to a mechanic if you have any good ones in the area. It sounds like you may need a break out box to figure out the problem. You could unplug the 42 pin connection on the drivers side valve cover and see if the computer acts any different. Sorry if I was being rude.

 

Hey guys, I've been gone for a bit. Sorry. We just weathered a 4 day unprecedented wind and rain storm. More than half BC Hydros customers were out of power for 3 days. And internet was just restored yesterday. Ive been on damage control for a week now, and working emergency services digging up broken power lines. Little burnt out and hope to get back on the truck this weekend. So no finds yet. I just got back online so noticed your recent posts. Thank you. I will try unplugging all the sensors mentioned, and work on the other suggestions. I've been alittle over whelmed, so I will post my results. Thanks for your patients.