Solved 2010 Explorer Sport Trac XLT - multiple PCM failures?

[yabyums61]

Hi all





Looking for a little help with the truck. Although old it has only 35,000 miles on the original motor and is otherwise in perfect shape. I bought it from the original owner, who used it for light duty only. It's a beautiful truck, but has a persistent PCM or wiring problem I need some help on


When driving on hilly and twisty terrain the truck, which is normally very smooth on flat pavement, will suddenly give a palpable "clunk" and go into limp mode, with erratic transmission shifting. At the same time the following dash lights come on: Check Engine, Powertrain Wrench and (a little later) the RSC traction light. The speedometer also bounces erratically up and down, 0-25 mph. By turning off the ignition completely the truck resets for a while, but only until the conditions are ripe for the same problems to occur all over again


Last month my Ford-trained mechanic replaced the PCM (~$1000 USD), following a code check that showed it was faulty. There was some difficulty programming the used PCM replacement, but eventually it was successfully programmed by VIN #. But all the above problems came back on my first day with the truck after the PCM service. I took the Explorer back to the mechanic, and drove the truck with him on hilly terrain until the clunk was felt and all the problems took hold. He drove the truck on with his diagnostic computer running tests, which during the driving pointed to a bad Vehicle Speed Sensor in the left front wheel. But after further testing in the shop, I was told that the replacement PCM is also faulty. I find this hard to believe: two faulty PCMs !?!?


From some online research on this site and others I am being to think the Explorer might have a problem with the upper wiring harness on the engine, which someone referred to as the RSC wiring harness


I'm hoping someone from Ford or on this site recognizes the problem I am having and can point us in the right direction -- it's a beautiful truck and I'm certain the issue is worth the time to figure out (but maybe with a little help from you, friends)

 

[Fix4Dirt]

a

Hi all





Looking for a little help with the truck. Although old it has only 35,000 miles on the original motor and is otherwise in perfect shape. I bought it from the original owner, who used it for light duty only. It's a beautiful truck, but has a persistent PCM or wiring problem I need some help on


When driving on hilly and twisty terrain the truck, which is normally very smooth on flat pavement, will suddenly give a palpable "clunk" and go into limp mode, with erratic transmission shifting. At the same time the following dash lights come on: Check Engine, Powertrain Wrench and (a little later) the RSC traction light. The speedometer also bounces erratically up and down, 0-25 mph. By turning off the ignition completely the truck resets for a while, but only until the conditions are ripe for the same problems to occur all over again


Last month my Ford-trained mechanic replaced the PCM (~$1000 USD), following a code check that showed it was faulty. There was some difficulty programming the used PCM replacement, but eventually it was successfully programmed by VIN #. But all the above problems came back on my first day with the truck after the PCM service. I took the Explorer back to the mechanic, and drove the truck with him on hilly terrain until the clunk was felt and all the problems took hold. He drove the truck on with his diagnostic computer running tests, which during the driving pointed to a bad Vehicle Speed Sensor in the left front wheel. But after further testing in the shop, I was told that the replacement PCM is also faulty. I find this hard to believe: two faulty PCMs !?!?


From some online research on this site and others I am being to think the Explorer might have a problem with the upper wiring harness on the engine, which someone referred to as the RSC wiring harness


I'm hoping someone from Ford or on this site recognizes the problem I am having and can point us in the right direction -- it's a beautiful truck and I'm certain the issue is worth the time to figure out (but maybe with a little help from you, friends)

View attachment 432865

are there any codes? i dont have much reason to believe both pcms are faulty. that would be the last thing i would check unless theres a U code or a lost comm code then i would check wiring etc still

 

[Bazz270]

What error code do you have now?
Without the codes retrieved we are probably can tell you nothing about.

 

[dogbus]

Hi all





Looking for a little help with the truck. Although old it has only 35,000 miles on the original motor and is otherwise in perfect shape. I bought it from the original owner, who used it for light duty only. It's a beautiful truck, but has a persistent PCM or wiring problem I need some help on


When driving on hilly and twisty terrain the truck, which is normally very smooth on flat pavement, will suddenly give a palpable "clunk" and go into limp mode, with erratic transmission shifting. At the same time the following dash lights come on: Check Engine, Powertrain Wrench and (a little later) the RSC traction light. The speedometer also bounces erratically up and down, 0-25 mph. By turning off the ignition completely the truck resets for a while, but only until the conditions are ripe for the same problems to occur all over again


Last month my Ford-trained mechanic replaced the PCM (~$1000 USD), following a code check that showed it was faulty. There was some difficulty programming the used PCM replacement, but eventually it was successfully programmed by VIN #. But all the above problems came back on my first day with the truck after the PCM service. I took the Explorer back to the mechanic, and drove the truck with him on hilly terrain until the clunk was felt and all the problems took hold. He drove the truck on with his diagnostic computer running tests, which during the driving pointed to a bad Vehicle Speed Sensor in the left front wheel. But after further testing in the shop, I was told that the replacement PCM is also faulty. I find this hard to believe: two faulty PCMs !?!?


From some online research on this site and others I am being to think the Explorer might have a problem with the upper wiring harness on the engine, which someone referred to as the RSC wiring harness


I'm hoping someone from Ford or on this site recognizes the problem I am having and can point us in the right direction -- it's a beautiful truck and I'm certain the issue is worth the time to figure out (but maybe with a little help from you, friends)

View attachment 432865

I had very similar problems with a 2008 Ford Explorer XLT. I myself believed the PCM was faulty or something else was wrong. I replaced the throttle position sensor and got some wiring redone by Aamco. Less than a thousand miles later and the transmission blew while while driving on normal city roads. Still have no idea what the actual problem was but maybe you had a P0225 code? Or you might end up buying a whole new transmission at some point.

 

[yabyums61]

I had very similar problems with a 2008 Ford Explorer XLT. I myself believed the PCM was faulty or something else was wrong. I replaced the throttle position sensor and got some wiring redone by Aamco. Less than a thousand miles later and the transmission blew while while driving on normal city roads. Still have no idea what the actual problem was but maybe you had a P0225 code? Or you might end up buying a whole new transmission at some point.

Thanks for your info. It seems right now like I have a shortcircuit in the engine wiring harness, which connects the PCM to about 60 parts of the car. Either that or one of the 60 parts is shorted out the OEM computer. The problem I now have is that Ford discontinued the wiring harness for this model pickup some years back, and I am finding a replacement harness extremely hard to source at present.

If anyone knows a source for electrical parts for a 2010 Ford Explorer Sport Trac XLT and can give me a good steer I'll be forever indebted to them ... I will soon post the error codes the PCM is throwing off, please pardon the delay

 

[dogbus]

Thanks for your info. It seems right now like I have a shortcircuit in the engine wiring harness, which connects the PCM to about 60 parts of the car. Either that or one of the 60 parts is shorted out the OEM computer. The problem I now have is that Ford discontinued the wiring harness for this model pickup some years back, and I am finding a replacement harness extremely hard to source at present.

If anyone knows a source for electrical parts for a 2010 Ford Explorer Sport Trac XLT and can give me a good steer I'll be forever indebted to them ... I will soon post the error codes the PCM is throwing off, please pardon the delay

I actually drive a 2007 Sport Trac right now so if I can figure anything out for myself I'll let you know. I believe Aamco replaced my engine wiring harness but might not have charged me for that given the other circumstances of the repair so I don't know the specifics.

 

[yabyums61]

will check Aamco out

 

[yabyums61]

I wanted to update this case and close it out. The problem turned out to be a bad transmission wiring harness, a part which has been discontinued by Ford but was available at the local Ford dealer in Medellin Colombia where I live. They were multiple connectors on the OEM harness that were completely corroded. This caused the transmission to enter limp mode and lit up the dash warning lights

I want to thank everybody who responded to my request for help. Glad to know you, and to have this place as a resource

 

[Fix4Dirt]

I wanted to update this case and close it out. The problem turned out to be a bad transmission wiring harness, a part which has been discontinued by Ford but was available at the local Ford dealer in Medellin Colombia where I live. They were multiple connectors on the OEM harness that were completely corroded. This caused the transmission to enter limp mode and lit up the dash warning lights

I want to thank everybody who responded to my request for help. Glad to know you, and to have this place as a resource

thanks for telling us what the fix is! glad the trac is back up and running, and that al is good!