4.0 ECM troubles

[holmes1]

2001 4.0 4x4 Ranger
I have a "check engine" light, but the code reader says that there is a power problem. There isn't power to the code reader jack on the pin that there should be power. This vehicle hasn't been wrecked, and the wiring looks good. I've had problems with the ECM before, when it acted like it had been disconnected, and had to reboot.
If this is indeed an ECM problem, how do I find the correct one to replace it? The wrecking yards show about a dozen or more ID's for them. Where is the ECM id?
Thanks
DM

 

[MAKG]

So, how do you know your code reader isn't jacked?

 

[96xltV6]

autozone has code reading for free, go to there and see if theirs works.

 

[holmes1]

My code reader is fine, and works with my GM products. There is no power on the pin that is supposed to have power. I believe the trouble is in the ECM, but I don't know which one to buy. I'm sure that Ford would sell me one for what I make in a month.

 

[Bird]

Check your fuses - one of them passes voltage to that pin.............

Bird

 

[holmes1]

2001 4.0 4x4 Ranger
I have a "check engine" light, but the code reader says that there is a power problem. There isn't power to the code reader jack on the pin that there should be power. This vehicle hasn't been wrecked, and the wiring looks good. I've had problems with the ECM before, when it acted like it had been disconnected, and had to reboot.
If this is indeed an ECM problem, how do I find the correct one to replace it? The wrecking yards show about a dozen or more ID's for them. Where is the ECM id?
Thanks
DM

I took it to Auto Zone. They couldn't get the code either. There are no fuses blown, and the harness hasn't been damaged. I think that the problem is with the ECM. I had an EGR problem previously, and retrieved the code for that. This problem started a while back when the computer acted like it had lost it's power. I just want to be sure before I buy another ECM.
DM

 

[rags]

I agree with bird, Take a look at the fuses again, I worked on a 2000 explorer 4.0 that had a check engine light on and my code reader was blank! I also thought the problem was with my scanner, but it worked on other vehicles.

As i was working on other problems with the vehicle like the cigerette lighter not working, I found its fuse blown. After replaceing the fuse for the lighter the code reader worked!

Check that circuit First!

 

[Kona]

Just had a similar problem , it was the ECM Relay! $200 later I got it back from Ford all fixed and it has been great since.

 

[holmes1]

I agree with bird, Take a look at the fuses again, I worked on a 2000 explorer 4.0 that had a check engine light on and my code reader was blank! I also thought the problem was with my scanner, but it worked on other vehicles.

As i was working on other problems with the vehicle like the cigerette lighter not working, I found its fuse blown. After replaceing the fuse for the lighter the code reader worked!

Check that circuit First!

I think that we're onto something. Since I don't smoke, I didn't realize the lighter didn't work. However, no fuses are blown, and the neither the Ford manual or the Chilton's manual lists anything about the lighter fuse. It must be a circuit breaker, since no fuse is blown, but which one? I can find no reference to the lighter on the schematic either.
DM

 

[rags]

The Lighter is on a fuse, I looked through the owners manual and found it, it is in the fuse box inside the drivers side of dash.

 

[holmes1]

The Lighter is on a fuse, I looked through the owners manual and found it, it is in the fuse box inside the drivers side of dash.

You are absolutely correct. I didn't think to look for another fuse panel. I figured that one fuse panel was all there was. But in the book, it says that the fuse is for the lighter and the data port. Thanks!!!! This forum has just saved me at least $145 for Ford's diagnosis!
DM

 

[rags]

Glad we could be of help! Like I said I found it by accident.

Hopefully a new fuse will be ok, but if it blows right away thats a whole new problem. But at least you are on the right track.

 

[Bird]

You're welcome................

Bird

 

[holmes1]

You are absolutely correct. I didn't think to look for another fuse panel. I figured that one fuse panel was all there was. But in the book, it says that the fuse is for the lighter and the data port. Thanks!!!! This forum has just saved me at least $145 for Ford's diagnosis!
DM

Well, now I have the codes, PO171 and PO174. The code reader handbook says it is "system too lean" on right and left banks. TRS says it is an oxygen sensor/fuel system problem. Neither is of much help.

 

[Bird]

Look for unmetered air getting into the intake from either a broken vacuum line or a line not connected up.

Bird