SOLVED - HELP! No crank, no start, and no communication with PCM

[Adam Robert]

I am working on a 2002 Sport Trac 4.0 SOHC

When I try to start the truck, there is no crank and it does not start. All of the lights on the dash come and go as normal, except the theft light remains unchanged, with slow and steady flash. All other electronics seem to work appropriately. I fear this could be a lot of things and I have already eliminated the following.

The big one, I have confirmed my PCM is good. I have another ST and it will communicate when swapped with It. Putting the other PCM in this one does not correct the issue.

The OBD port does seem to have power as it does turn on my scanner, but the scanner shows no communication.

The battery is good, I also used a new one from my other ST to check.

I do not think it’s the ignition immobilizer, the PATs, or a bad key. The theft light never changes from its slow flash, regardless of key position or if it’s in at all. If it were either of those, the theft would flash quickly if there’s an issue or disappear completely if there’s isn’t one and a good key is in.

I have checked all of the appropriate fuses and they all seem fine. Some of them looked sort of dirty, but weren’t blown (tested) and still made a connection. I either replaced or cleaned them up.

The PCM diode was tested and is functional.

I’m really unsure where to go from here. I’m terrible on the electronics, but I’m trying desperately to figure it out. I’m wondering if this could be an issue with a relay or fuse making a poor connection? I’ve moved some relays around with no change. I’d love it if someone could help me sort this out. Thank you so much, in advance.

 

[oklagp1200r]

Have you tried disconnecting the battery to drain the systems? Try it doth + and - for about 30 minutes then see what happens. Did this problem just happen out of the blue?

 

[Adam Robert]

Have you tried disconnecting the battery to drain the systems? Try it doth + and - for about 30 minutes then see what happens. Did this problem just happen out of the blue?

It’s been good and drained for sure.

I actually just purchased this truck as a project. They said this no crank issue did start out of nowhere. They had an aftermarket anti theft device installed and they thought maybe that went bad… maybe. All that system consisted of was a special relay that would replace the relay for the starter and would link to a fob. When you activate the fob, the relay gives 30 seconds to start the car. I have replaced the relay with a normal one. Either way, this wouldn’t cause the no communication issue.

 

[Fix4Dirt]

It’s been good and drained for sure.

I actually just purchased this truck as a project. They said this no crank issue did start out of nowhere. They had an aftermarket anti theft device installed and they thought maybe that went bad… maybe. All that system consisted of was a special relay that would replace the relay for the starter and would link to a fob. When you activate the fob, the relay gives 30 seconds to start the car. I have replaced the relay with a normal one. Either way, this wouldn’t cause the no communication issue.

starter condition? is there a way to bypass that aftermarket anti theft system?

 

[Adam Robert]

starter condition? is there a way to bypass that aftermarket anti theft system?

The anti theft system was removed. It was nothing more than a special relay that would only work when a key fob told it to. I replaced it with a normal/ working relay, so that is now a non factor.

Ultimately this really seems like an issue directly related to getting the PCM to communicate. I am most hopeful right now that it’s a wire connection somewhere that has gone bad, either at the fuse box or at the PCM connector. I’m going to get a light up tester to see it that tells me anything.

 

[429CJ-3X2]

Here's the link to the thread when I had a similar problem with my '01 Sport Trac.

Solved - 2001 Sport Trac - no crank

My 18 yr old moved out 2 weeks ago and took my '01 Sport Trac with her. (It is our "spare" vehicle - her boyfriend is driving her car.) She came over tonight, and mentioned the turn signals weren't working. Neither were the brake lights. I started checking fuses, but because it's cold, windy...

www.explorerforum.com

My original no start problem - which had the same symptoms as you describe - was caused by the wires pulling out of the multi-function switch when my daughter lowered the tilt steering wheel all the way.
Then when I checked the fuses, I missed getting fuse #19 for the PCM back in.

 

[Adam Robert]

Here's the link to the thread when I had a similar problem with my '01 Sport Trac.

Solved - 2001 Sport Trac - no crank

My 18 yr old moved out 2 weeks ago and took my '01 Sport Trac with her. (It is our "spare" vehicle - her boyfriend is driving her car.) She came over tonight, and mentioned the turn signals weren't working. Neither were the brake lights. I started checking fuses, but because it's cold, windy...

www.explorerforum.com

My original no start problem - which had the same symptoms as you describe - was caused by the wires pulling out of the multi-function switch when my daughter lowered the tilt steering wheel all the way.
Then when I checked the fuses, I missed getting fuse #19 for the PCM back in.

Was the no communication issue likely due to the fuse then?

 

[Fix4Dirt]

Was the no communication issue likely due to the fuse then?

if theres no fuse or a blown fuse circuit is open, so there would be no power to PCM

 

[Adam Robert]

if theres no fuse or a blown fuse circuit is open, so there would be no power to PCM

Unlikely the multifunction switch has anything to do with then no crank issue then. I need to get a light meter on the fuse box and confirm power is getting there.

 

[Fix4Dirt]

maybe also check starter relay, and battery connections, had that one before

 

[Adam Robert]

maybe also check starter relay, and battery connections, had that one before

The starter relay was replaced (was previously a weird special aftermarket anti theft relay). The battery itself is good and the connection seems fine as every other electric works no problem.

 

[429CJ-3X2]

As I said above, my original no start issue was because the wires pulled out of the multi-function switch when my daughter lowered the tilt wheel. This is a common issue.

 

[Adam Robert]

As I said above, my original no start issue was because the wires pulled out of the multi-function switch when my daughter lowered the tilt wheel. This is a common issue.

Understood. I don’t think that alone would not cause the no communication issue though. That is my primary concern as getting that resolved will make troubleshooting anything else easier.

 

[429CJ-3X2]

Why come on here asking for help if you're going to quickly dismiss suggestions from someone who dealt with the same problem?

When everything is working correctly, your scanner won't connect to the truck unless the key is "on", correct?

Power for everything that operates with the key in the on, run, or start positions goes through the multi-function switch (MFS). If one or more wires into or out of the MFS is loose, broken, or disconnected, you'll have an open circuit and something isn't going to work. This is a well documented problem.
Assuming the truck has a tilt steering wheel, move it to the highest position and see if anything changes. If it does, you definitely have loose wires in the MFS. If it doesn't change anything, you might still have loose wires in the MFS.

That's all I have. I'm done.

 

[Sager]

I am working on a 2002 Sport Trac 4.0 SOHC

When I try to start the truck, there is no crank and it does not start. All of the lights on the dash come and go as normal, except the theft light remains unchanged, with slow and steady flash. All other electronics seem to work appropriately. I fear this could be a lot of things and I have already eliminated the following.

The big one, I have confirmed my PCM is good. I have another ST and it will communicate when swapped with It. Putting the other PCM in this one does not correct the issue.

The OBD port does seem to have power as it does turn on my scanner, but the scanner shows no communication.

The battery is good, I also used a new one from my other ST to check.

I do not think it’s the ignition immobilizer, the PATs, or a bad key. The theft light never changes from its slow flash, regardless of key position or if it’s in at all. If it were either of those, the theft would flash quickly if there’s an issue or disappear completely if there’s isn’t one and a good key is in.

I have checked all of the appropriate fuses and they all seem fine. Some of them looked sort of dirty, but weren’t blown (tested) and still made a connection. I either replaced or cleaned them up.

The PCM diode was tested and is functional.

I’m really unsure where to go from here. I’m terrible on the electronics, but I’m trying desperately to figure it out. I’m wondering if this could be an issue with a relay or fuse making a poor connection? I’ve moved some relays around with no change. I’d love it if someone could help me sort this out. Thank you so much, in advance.

May be simplistic, but did you try starting it in neutral?

 

[Adam Robert]

May be simplistic, but did you try starting it in neutral?

I have, but similar to the multifunction switch, that wouldn’t have any impact on ability to communicate with the PCM. That is my primary concern right now as solving that is likely to solve all.

 

[Adam Robert]

SOLVED!

This was ultimately something incredibly simple, but took a lot of time and trouble shooting, including buying wiring diagrams, tearing apart the engine fuse box, and tracking wires.

Keep in mind, I just bought this truck as a flip project. Its a 2002 and it didn't start when I got it. I removed the aftermarket theft system. I checked that all the fuses that were there worked and ensured I did indeed have all of the needed fuses for the PCM, PATS, and starter. I am terrible at the electrical side of things, but as a certified Youtube mechanic, I found a way to learn. I used a test light to test the fuse box where the PCM relay should go (#54) and one of the inputs wasn't receiving positive power when it should. I learned it was directly connected to the PCM diode (#53) and I test it, which also was not receiving positive charge. I traced that wire to the inside of the cab and the inside fuse box. It lead to fuse #19, which was not there. THIS is where it got interesting. On a 2002, the #19 fuse is for trailer tow lights and this truck isn't setup for towing, so it would make sense that it was missing entirely. For a 2000-2001 model, this fuse IS for the PCM diode though. So, I started checking each fuse one at a time and immediately started to notice that this truck is actually wired like a 2001, not a 2002. I put in the 25 amp fuse that it called for.... IT WORKED!

Again, this was ultimately something so simple, but on the surface it wasn't simple at all. I'm not sure if this solution will ultimately help anyone, but I hope it does. There are a few of these posted, but almost none are listed as solved. Thank you to everyone who helped throw out ideas to work my brain on this solution.

 

[Fix4Dirt]

SOLVED!

This was ultimately something incredibly simple, but took a lot of time and trouble shooting, including buying wiring diagrams, tearing apart the engine fuse box, and tracking wires.

Keep in mind, I just bought this truck as a flip project. Its a 2002 and it didn't start when I got it. I removed the aftermarket theft system. I checked that all the fuses that were there worked and ensured I did indeed have all of the needed fuses for the PCM, PATS, and starter. I am terrible at the electrical side of things, but as a certified Youtube mechanic, I found a way to learn. I used a test light to test the fuse box where the PCM relay should go (#54) and one of the inputs wasn't receiving positive power when it should. I learned it was directly connected to the PCM diode (#53) and I test it, which also was not receiving positive charge. I traced that wire to the inside of the cab and the inside fuse box. It lead to fuse #19, which was not there. THIS is where it got interesting. On a 2002, the #19 fuse is for trailer tow lights and this truck isn't setup for towing, so it would make sense that it was missing entirely. For a 2000-2001 model, this fuse IS for the PCM diode though. So, I started checking each fuse one at a time and immediately started to notice that this truck is actually wired like a 2001, not a 2002. I put in the 25 amp fuse that it called for.... IT WORKED!

Again, this was ultimately something so simple, but on the surface it wasn't simple at all. I'm not sure if this solution will ultimately help anyone, but I hope it does. There are a few of these posted, but almost none are listed as solved. Thank you to everyone who helped throw out ideas to work my brain on this solution.

thanks for posting a solution! always great to hear back! glad its resolved!

 

[429CJ-3X2]

Glad you got it fixed. I should have reread my thread I linked to. I thought my truck originally wouldn't start because of the MFS, which can cause all kinds of problems. Her complaint was lights not working, which was the MFS, but I caused the no start problem by getting the fuse in the wrong place. I should have reread my thread more carefully.
Fuse 19 was the one I put in the wrong place causing the no start. Again that was an '01, but as you discovered, the model year isn't always a definitive line when it comes to changes. I recently found the factory 2002 Sport/Sport Trac Service Manual covers rear disc brakes which weren't on Sport Tracs until 2003. Now I'm curious about what Fuse 19 is for in my '02. My '01 has an early August '01 build date, which means it's probably the same as an '02. I'd bet my '02 won't start if I pull fuse 19.

As far as your truck not being set up for towing, I don't think there was a factory tow package for the 1st Gen Sport Tracs, just the hole in the bumper for a ball. (I don't recommend towing with tge bumper. Only 4 bolts hold it on.) They all should have wiring for a trailer all the way to the back, including the pigtail which mounts to the left of the license plate. My '02 was as stripped down as they came, and it has the pigtail.

 

[Adam Robert]

Glad you got it fixed. I should have reread my thread I linked to. I thought my truck originally wouldn't start because of the MFS, which can cause all kinds of problems. Her complaint was lights not working, which was the MFS, but I caused the no start problem by getting the fuse in the wrong place. I should have reread my thread more carefully.
Fuse 19 was the one I put in the wrong place causing the no start. Again that was an '01, but as you discovered, the model year isn't always a definitive line when it comes to changes. I recently found the factory 2002 Sport/Sport Trac Service Manual covers rear disc brakes which weren't on Sport Tracs until 2003. Now I'm curious about what Fuse 19 is for in my '02. My '01 has an early August '01 build date, which means it's probably the same as an '02. I'd bet my '02 won't start if I pull fuse 19.

As far as your truck not being set up for towing, I don't think there was a factory tow package for the 1st Gen Sport Tracs, just the hole in the bumper for a ball. (I don't recommend towing with tge bumper. Only 4 bolts hold it on.) They all should have wiring for a trailer all the way to the back, including the pigtail which mounts to the left of the license plate. My '02 was as stripped down as they came, and it has the pigtail.

All good and I do appreciate your help. Really wild that ultimately it was fuse 19 for both of us and both sort of due to dumb luck. I can't believe the effort and head pounding I went through to figure it out, but I am honestly better for it as I did learn some lessons. Thank you again.