ECM and Transmission troubles

[Big91explorer]

Well, I've gone through 2 transmission in my 94 explorer with an A4LD and i've tried 2 different ECM's I have the F47F-12A650-MB ECM, and I'm not sure if it's even the right ECM for the truck.

My problem is that, It will not shift into OD or lock up the TC, I know the OD and TC solenoids work, because I wired up a switch to them and can manually shift it, but I want it to function correctly.

So...How many ECM options are there for an 94 explorer 4.0 A/T?

Any idea's would be appreciated. Thanks.

 

[MrShorty]

Can you describe how you wired them in to manually shift?

Next thing I'd do would probably be:

1) Get a voltmeter and make sure there is +12 V at the appropriate transmission connector. The two solenoids share a common power supply, when they both aren't functioning, one might be inclined to look at what they have in common. Get a wiring diagram (even the one in Chiltons is often adequate for these circuits) if you need to see which wire to probe.

2) While you have the wiring diagram and voltmeter out, hook up the meter to measure voltage drop across either solenoid. Enter output state test (see my "notes on pulling EEC-IV codes" thread) and then see if you can get the computer to cycle the solenoids.

 

[90ranajo]

You should have either a F37F-ZB or a F37F-AAB.

 

[Big91explorer]

Can you describe how you wired them in to manually shift?

Next thing I'd do would probably be:

1) Get a voltmeter and make sure there is +12 V at the appropriate transmission connector. The two solenoids share a common power supply, when they both aren't functioning, one might be inclined to look at what they have in common. Get a wiring diagram (even the one in Chiltons is often adequate for these circuits) if you need to see which wire to probe.

2) While you have the wiring diagram and voltmeter out, hook up the meter to measure voltage drop across either solenoid. Enter output state test (see my "notes on pulling EEC-IV codes" thread) and then see if you can get the computer to cycle the solenoids.

Basically all I did was the TC lock up mod for the OD and TC solenoids, That was the first thing I did, was check the voltage at each terminal, I have a good 12v on the Positive side, and these work by groungind to the ECM when it wants to shift, That's when I did a little test, and just wire up a grounded switch to (what is it, pins 51 and 53?) about 2 inches from the ECM, so I know the wires are good, because the switches are wired so close to the ECM. When I flip the switch, I can get OD, and only if i'm in the OD selector on the gearshift. So, I know that they will function.

Do you have a link to the "notes on pulling EEC-IV codes" thread" I am new to this forum, and havn't had much practice searching.

So, basically, I know that the solenoids will function, it's just a matter of getting the computer to engage them, and that's what i'm up against, I already have a new TPS, the MAF is good, VSS i'm not sure about, but my cruise control works, so I believe it's good. And that's what leads me up to believing I have the wrong ECM.

 

[Big91explorer]

You should have either a F37F-ZB or a F37F-AAB.

DO you know this for certain? How would I go about finding out which ECM that I need?

 

[Big91explorer]

Ok, so I pulled the codes today,

I get KOEO

566
and
629

But, like I said, I hooked up switches to the wires about 2 inches away from the ECM, and I can engage the solenoids that way.

PLEASE HELP ME.

 

[MrShorty]

Do you have a link to the "notes on pulling EEC-IV codes" thread" I am new to this forum, and havn't had much practice searching.

I don't keep a quick link anywhere, but it's one of the stickies in the EEC-IV forum, which you can easily access with the forum jump menu near the bottom of the page.

KOEO 566 and 629 indicate the PCM is seeing a circuit fault in those two circuits. My experience says that the fault will either be a full open or a short to ground, so it shouldn't be too hard to track down (unless the break/short is inside the PCM, which doesn't seem too likely where you've replaced the PCM once).

But, like I said, I hooked up switches to the wires about 2 inches away from the ECM, and I can engage the solenoids that way.

This suggests that the circuit fault is not upstream of the point that you connected your ground switch. I'd probably carefully check the wiring between the splice point and the PCM, including the PCM 60 pin connector.

 

[Big91explorer]

Ok, Ya, I found the link.

Well, considering there is only about an inch or two of wire inbetween the splice and the PCM, I am gonna say this is good.

First ECM was garbage. Current one works, and these are the only codes that I get in the whole process.

What does pin 60 do?

And like I said, I can flip the switch, and the solenoid activates, and I've got 12+v at the connector. So, I think it's either the ECM, or something that controls it. I dunno, I am stumped. I have been tracing this gremlin for about 4 months.

 

[MrShorty]

The wiring diagram in Chiltons says pin 60 is a ground.

and I've got 12+v at the connector.

Which connector?

 

[BrooklynBay]

The middle wire on the 3 prong connector on the transmission should have +12 volts. MrShorty, it might be a good idea to place a link to your thread on pulling codes in your signature for future reference.

 

[Big91explorer]

Yes, and that's where I have 12v. Plus I know it has 12v because I can ground it out, 2 inches from the ECM and it will shift.

What are the chances that I have 2 ecm's with a blown OD and TC circuit? I can get a great deal on a reman ECM from napa. But it's still a good chunk of cash, especially if it does not fix my problem.

Today I spliced in another ground to pin 60, about an inch from the ECM. Didn't change anything. I also adjusted the shift linkage and it's spot on. I am so frustrated.

The codes I gave bring up both the OD and TC bad circuit. If everything else checks out. Does that mean it's a bad circuit inside the ECM?

 

[BrooklynBay]

Check the output from the computer's wiring harness for a ground from the computer's end instead of at the transmission. The computer might be sending out a ground, but the wiring harness might have a broken connection. Another thing that you could do is check the continuity of the overdrive, and torque converter clutch wiring from each point (computer to the transmission).

 

[Big91explorer]

Check the output from the computer's wiring harness for a ground from the computer's end instead of at the transmission. The computer might be sending out a ground, but the wiring harness might have a broken connection. Another thing that you could do is check the continuity of the overdrive, and torque converter clutch wiring from each point (computer to the transmission).

I dont think your realizing that, I have a ground spliced into the wires that go to the Solenoid's about an Inch from the ECM. SO, I now for a fact that the wires are good. from that point to the transmission.

 

[MrShorty]

What are the chances that I have 2 ecm's with a blown OD and TC circuit?

I would say little chance you would pull two used PCM's off the shelf and have both fail internally in the OD and TCC solenoid circuits. Not impossible, mind you, just not likely.

If everything else checks out. Does that mean it's a bad circuit inside the ECM?

That's the usual, "by-the-book" way of diagnosing a bad PCM -- process of elimination. When all else checks out good, then the PCM must be at fault.

One likely candidate between the splice point and the PCM would be the connector. Perhaps those two pins have corroded, or pushed out, or broken, or ???. That would probably be the next thing I'd do -- disconnect the PCM and inspect those pins.

 

[Big91explorer]

I would say little chance you would pull two used PCM's off the shelf and have both fail internally in the OD and TCC solenoid circuits. Not impossible, mind you, just not likely.

That's the usual, "by-the-book" way of diagnosing a bad PCM -- process of elimination. When all else checks out good, then the PCM must be at fault.

One likely candidate between the splice point and the PCM would be the connector. Perhaps those two pins have corroded, or pushed out, or broken, or ???. That would probably be the next thing I'd do -- disconnect the PCM and inspect those pins.

Ya, I think I have eliminated everything, but just not sure if i'm missing something. Any sensors or switches, etc....

Ya, I will unplug it again, and check the pins out. I'm pretty sure it's the ECM, but I just dont want to spend that much money, just to find out it still didnt fix the problem.

And I called the ford dealership, I had them run the VIN # and they confirmed that this is the right ECM for the truck. F47F-12A650-M* He couldn't exactly tell me what the asterisk was about though.

 

[doonze]

I am way out of my depth here, you have MrShorty our resident electronics expert and Brooklynbay, or resident 1st gen auto tranny guru!

However, my thought is maybe the ECM isn't getting the siginal your in OD on the selector? I know it's working for you with your switch setup only if your in OD, so the switches know, but my question is, can you verify the PCM knows??

 

[Big91explorer]

I am way out of my depth here, you have MrShorty our resident electronics expert and Brooklynbay, or resident 1st gen auto tranny guru!

However, my thought is maybe the ECM isn't getting the siginal your in OD on the selector? I know it's working for you with your switch setup only if your in OD, so the switches know, but my question is, can you verify the PCM knows??

See, and I can't verify that at all, I can't find any info on what tells the ECM that the selecter is in OD.

But... I can turn the switch ON (activated) and have the gear selector in D and it wont shift into OD, but when I switch the gear selector into OD, then the trans will shift into OD. The whole time the switch is activated.

 

[BrooklynBay]

Have you tested various parts such as the VSS & TPS, and cleaned the MAF sensor? Are you using LED tail light bulbs?

 

[Big91explorer]

Yes, I cleaned the MAF, it idles great, and runs strong, At first I thought it was the TPS, so I bought a new one from napa. Like I said, engine runs smooth and strong.

The VSS, i havn't tested or replaced, but the cruise control works great. Holds a good steady speed uphill, or downhill. But I havn't tested it or replaced it.

Are there any other sensors that would 'cause this problem? I just want to go through all my options before I buy another ECM.

Thanks guys (gals?), for all the help so far. Keep them coming.

 

[BrooklynBay]

Test the ECT sensor. The PCM won't let it go into overdrive if it detects that it's too cold. A cold reading will also make a rich mixture, and sometimes cause a gasoline smell, and hard starting. It might make it feel like it has a little more power. LED tail light bulbs might cause a problem with the TCC solenoid.