no, that is less than one ohm.

 

So dead end. Test one. have voltage . Test two, is the resistance greater than 10,000ohms. No its open, stays at 1 on meter. Or is that yes since its open it has 100%resistance. Confused. I'll try both routes. Step 3 same test pcm out. Again its open. so yes or no. Guessing yes. Says to put in a new pcm. Retest, same thing. If its no, then I have a short to ground on pin 80. I don't know what the numbers on my meter mean. Turned to ohms, it reads 1 . Touch the leads, it reads 00.0. So testing it stays at 1 . So what is that reading. Means open, no connection to me. So, if 1 means over 10000ohms then it says put in a new pcm. Retest. So no difference. If it means less than 10000ohms then it means there is a short to ground. Help

 

Im totally lost. havnt a clue how to get past test 2. It doesn`t offer a direction to go if the circuit is open. Can`t move forward, tried the new pcm. no difference. So no direction to go on these tests.

 

The 1 on your meter indicates the value is higher than your meter can read, basically an open circuit and over 10,000 ohms. From there you go to test #4 which checks the relay and if it is not the relay you go to 5 which checks for an open in the circuit which at this point seems likely since you have already ruled out the PCM in another truck right?

 

So heres my delema. First, I don't know how to read the ohm meter. Second the test starting with two, doesn't say with the relay in or out?? If I take it out and read pin 86 then it reads the .23, less than an ohm I'm told. if I put the relay in and probe the back of the fuse panel wh/blk then it is open, or 1 . on the meter. First off, whats 1 mean. Second, if its over 10000 ohm then it says put in a pcm. Retest. Both pcms aren't bad. its possible but unlikely. I think both are good. So basically I got a reading that doesn't give me a direction to continue.

 

Yes the new pcm was working in another truck for sure. So If I goto step 4 I get the same result. Its an open circuit. Key on and off. So I need to try a new IDM to move forward. I don't have one. I hate tossing expensive parts at this thing. Already looks like I have a spare pcm now. Guess I have to, to continue. I'll see if the wrecker has one and a fuse box too just in case.

 

If you get more than 5 ohms in step 4 you go to step 5. If you still get more than 5 ohms there is an open in the circuit, not the pcm. the wire

 

Thanks, my brain is fried. I better take a break. What is a break out box. I need one.

 

When I figure out what it is , were does the box go?

 

I don't know. I'm fed up. Don't have a clue what the break out box is or were they want you to put it to do the test. So I just probed the wh/blk wire at the fuse box and then at the pcm plug. It has no resistance, so again it tells me to put in a pcm. I give up. I'm sending both pcms to Jody so he can test if they are good. Its going to cost a fortune, but its the only way to know for sure. The new one was working fine, but apparently by this test its toast as well as my original which was also working. Its gonna take a few weeks to get back form Jody. Can't believe ford cant do that. I know Im wasting my time and money. But this testing in circles seems to always point at the pcm. So to go forward I have to know for sure. My gut tells me there fine, but god only knows. Im really at a loss. Spent a lot of money on this thing. Is it worth it anymore. 25k motor is what kills me. 25k dead motor.

 

Ok so heres the deal. Im beating my head against the wall trying to figure this out. Whats confusing me is the relays and the fact that every test I do points to a bad pcm. So I'm testing in circles not knowing whats causing the idm relay not to fire. I even jumpered it to fire it. No go. Whats confusing is the pcm relay has a ground as it should in order to close when the other side is powered. That relay works. When you look at the drawing for the idm relay, it has no ground. All poles are positive. From what I see, test pin 80 should be a ground, but its got 11volts. Then when the pcm relay trips it sends power down pcm terminal 87 to Idm relay terminal 85. So if 86 were a ground it would fire but its not. So how does that relay fire. This is the whole reason I suspect my fuse box is melted inside. Its possibly crossed in there sending power to the idm terminal 86 on the relay. This is why I don't think my pcm's are dead. Both of them. But because I don't know, I can't make any headway. So tomorrow I ship out both PCM's to Jody a DP Tuner. He is being gracious enough to test both PCM's for free, and because hes doing that I told him I would pay him to configure the new pcm to work with my single shots and put my vin in it for a spare. If they are good. Until I get them back in about 2 weeks( long ways away) I've decided to continuity test and ohm test every single wire on the pcm plug and Idm plug, and every wire out of the fuse box. So basically the whole truck. Lol. That way I know all my wires are good, and hopefully my pcm's are good, so when I get them back I can look for my issue with confidence its not the pcm or wires. That said, if they are all good, then it kinda means the fuse box is toast. I might take it apart to see if its melted in there. I notice its just clicked together in layers. Wrecker quoted me 150 for the fuse box and 300 for a spare IDM. Seems like a burn job to me. I thought a new IDM was only 150ish. Anyway. I may need one. I will repost when I find something and when I get the pcms back. Hopefully I've found a bad wire or something by then and I'm fixed ready to role. I think I might be dreaming. Hahaha

 

Sorry to hear that your head is spinning in circles

I wish I was of any help here but would like for you to keep us up on any new updates.

 

One more quick thought before I start testing again. It just occurred to me that maybe pin 80 is hot because the pcm IS gone and sending power instead of grounding??? Thoughts?? Not sure if that's possible, but if the fuse box can melt and cross, can't the pcm too? Odd that both pcms have the exact same problem if they are gone. Makes more sense to me that I was driving and the fuse box melted, sending power to terminal 86 cutting out the relay killing the truck. To me any ways. Any thoughts

 

No worries. When I figure this out I will post for everyone to learn. Nothing frustrates me more than finding a thread that is similar to my issue and reading it to get info, and the guy never posted the final result. Dead end post. So I will tell all. Im sure I'll be back soon looking for help on this. Lol.

 

A breakout box is a tool where you unplug the pcm and plug in the breakout box , giving you an easy way to check things because the breakout box has a test board with every terminal on it and you can do all the testing right there on the board.
You can still figure out stuff though, just like you ohmed out the wh/blk wire. So on the wht/blk you got a reading of 0.00?


I don't think there is anything wrong with your PCMs, I think it is a wiring issue. Could even be something shorted which is pulling down other things.


The IDM relay circuit is confusing but I think Thomas explained it pretty well. Circuits can ground through other loads which is how it works. A ground conductor carries an electrical potential if it is not grounded, once it becomes grounded that potential drops to zero and it becomes a true ground. Just like if you took a light bulb in your house and hooked up a black and a white wire, the bulb would light and you could touch the white wire all day and not get shocked because it is at zero potential to ground, because it is ground. But if you lift that white wire off the bus in the panel the light goes out and the white wire now has a 120 volt potential to ground. The 120 volts is coming up the black wire and passing thru the load (which in this case is the lamp filament) onto the white wire. Touch it now and you will get a shock.