Is an Engine Speed sensor necessary?

[Coffey1]

Yes something has to different! Four trucks so far do find with out. So something is going on here.
Now I really want to know why.

 

[Suprman]

The trans harness comes out the drivers side of the hump, goes along the drivers side frame rail there is a branch off to the throttle pos sensor and then it crosses over the trans, has a branch off to the output speed sensor and the main part mates with a pigtail coming off the trans housing. The engine speed sensor is not on the trans harness.

 

[Andyrv6av8r]

can each of you follow that wire to see where it goes? Andy maybe yours is misswired?? either by accident or as a work around before you got it ??

Mine is the factory harness and plug in plastic wire loom. It's hadn't been modified until I spliced in the replacement sensor.

 

[Andyrv6av8r]

Mine has a hard line in the way so it was hard to get a good angle.

 

[Suprman]

Wtec2 and 3 use the same cab body to trans harness. The wiring in the cab is different between the two though.

 

[Floridianson]

OK got to ask dumb question is the fluid at correct level in transmission?

 

[Andyrv6av8r]

OK got to ask dumb question is the fluid at correct level in transmission?

I have to ask; what does fluid level have to do with the sensor operation?

 

[Suprman]

Fluid level is a different sensor it’s inside the trans.

 

[coachgeo]

Confusing.. your opening paragraph says the code was "engine OR 'OUTPUT" speed sensor fault" right? So fixing the one on the engine bell housing.. which seems to be engine speed/rpm... never solved the issue; thus then it must not be engine speed/RPM sensor? Think it was Suprman's post that said another is the OUTPUT sensor. Process of elimination says it must be that one

 

[Suprman]

 

[Floridianson]

I will put five cents on the tail shaft sensor passenger side tail shaft.

 

[Andyrv6av8r]

Confusing.. your opening paragraph says the code was "engine OR 'OUTPUT" speed sensor fault" right? So fixing the one on the engine bell housing.. which seems to be engine speed/rpm... never solved the issue; thus then it must not be engine speed/RPM sensor? Think it was Suprman's post that said another is the OUTPUT sensor. Process of elimination says it must be that one

This thread is getting derailed big-time. Go back and read Post #4 on page 1. After replacing the speed sensor( post #1, page 1) in the bellhousing and adjusting it properly( post #4, page 1), the truck shifts fine. If I disconnect that sensor, it defaults to 2nd gear; I know that is the right one.

This explains the code I get with it disconnected.

https://youtu.be/auOZvpzSKJY

https://youtu.be/KKqPDQL6YHY

 

[Floridianson]

Which leads me to believe that there has to be a way to bypass this thing. Anybody have any input?

OK read you post #1 again my .02 your tcu program will not allow it? All sensors must be working on that truck engine and transmission to work correct. ? Does your truck have a winch?

Did find this and shows me how much I don't know.

 

[Coffey1]

No he has no winch.

 

[Ronmar]

Which brings me back to an earlier thought. The actual transmission input RPM sensor failed(passenger side bottom of the transmission about 2” back from where transmission joins with the engine bell), and some bright light did a field alt to use the engine RPM sensor to keep the vehicle operational... On an A0, unless you have an aux panel with a tach, or connect the STE/ICE test equipment, that sensor on the top of the engine bell is not used... None of the documentation shows any connection between that sensor and the transmission... I think you will ultimately find that your wiring has been hacked somewhere...

When you had the failed sensor or you did any of your testing with the engine RPM sensor disconnected and it faults to second gear, did your speedometer still work when you drove it?

 

[Andyrv6av8r]

Well I give credit to Floridianson and Coffey1 for their suggestions of checking the fluid level. I did and it took 2.5 quarts to bring it back up to the full mark. And believe it or not, the truck shifts fine with the sensor either connected or disconnected. I have no idea why it would always throw the 25 11 code upon disconnecting the sensor if fluid level was the issue. But so far, it is shifting just fine either way. I ran it for a couple of days disconnected and just today, reconnected it. Thanks everyone for your input and suggestions.

 

[Floridianson]

And I figured I derailed this thread bad. I do believe I was derailing as I failed to read what was typed. Glad you got it figured.

 

[Floridianson]

I don't know was looking at TM 9-2320-365-20-2. Page 2-1450. and code 25 starts on page 2-1448. Code 25 sub code 11 oil level, fuse, batteries, output speed sensor. If those were good then from there it wanted pressure test or replace WTECII TEPSS. Hope I don't confuse this maybe simple thing.

I just got lucky but the tm had the answer you were just looking at the speed sensor when it could have been batteries a fuse or fluid level.

 

[Coffey1]

You did good to lead me down same path lol.

 

[Ronmar]