Tach issue help

[Dirtleg]

Okay to cut to the chase. I have used 2 different tach sensors, my old one and a brand new one, and get the same results.

Description of the problem, when cold, my tach does not work. The transmission (E4OD) stays in "what the hell" mode and I have to manually shift it down to 1st every time I take off from a stop.

After driving the truck for about 15 minutes on the highway, tach comes on and all is good again.

It is very consistent. I drove this truck the same 50 mile distance 5 days in a row and the tach woke up within about a half mile of the same spot every time.

Since it acts identically with 2 different sensors, I am looking at the wiring. So far I have traced the wiring all the way to the firewall connector and both wires are showing 0.1 ohms resistance at the connector. I cannot find a wiring diagram for this circuit at the moment but the pics are the 1st and 3rd rows, 4th from the top.

Edit. Realized the plug goes into the TCM. So maybe a Bad TCM then.

Anyone ever experienced this issue? What was the solution if so?

Thanks

 

[Dirtleg]

Well at this point, I am 98% sure it is the TCM. One more test tomorrow and I'll have the answer.

I'll reflow the solder joints first before writing it off, but if that doesn't work, replacement will be required.

Sucks because I have been trying for years to find a donor for a manual swap. Do not want to spend any money on anything E4OD related for this truck. Was supposed to pick one up today about 75 miles from here but as I was hooking up my trailer dude texts and says instead of the $1500 we agreed upon 2 days ago, he wants 3k. F' that. He can keep it. Parts truck anyway.

 

[IDIBRONCO]

That's right. To Hades with him! I will say that all of a sudden, they seem to have taken a big jump in price around me too. It's not easy to find one for less than $1000 anymore. That makes me that much happier that I snagged the one with the transfer case that I did last spring for $500. Not to mention the one a couple of months by itself for $500. Those were two deals that didn't require any thinking. Just action, by that I mean saying "yes".

 

[Dirtleg]

So I just verified I have AC voltage at the sensor terminals(.6V at fast idle, .5V at normal idle) in the plug to the TCM while the truck is running. Verified relay was working and in addition to pin 1, which always has 12v, with the ignition on I have 12v power at pins 19, 37, 52, 53, 55 and 57.

Wish I could find a document that detailed the different connector wires and what they are for. Oh well I'll keep beating my head against a wall till I have a breakthrough. Only a matter of time.

 

[ttman4]

Sucks because I have been trying for years to find a donor for a manual swap. Do not want to spend any money on anything E4OD related for this truck. Was supposed to pick one up today about 75 miles from here but as I was hooking up my trailer dude texts and says instead of the $1500 we agreed upon 2 days ago, he wants 3k. F' that. He can keep it. Parts truck anyway.

Soooooo...... At $1500 I might be rich????? $3K I might be FILTHY RICH!!!!
Maybe I need to regroup, start counting how many I may have around here & tell Carol "I'm not HAULING OFF AFTERALL!!!"
BTW $1500, You talking bout the tranny or you talking bout the whole parts rig truck???

 

[IDIBRONCO]

BTW $1500, You talking bout the tranny or you talking bout the whole parts rig truck???

I read it as the transmission, but I might have misread it. I was talking about just the transmissions.

 

[DirtyWood]

Have you tried pulling any codes? If it is a new TCM I was able to find one on RockAuto for about $130 shipped.

 

[Dirtleg]

$1500 was the whole truck. Hasn't run in 8 years. Couldn't get an assessment of running condition, trans condition, brakes etc. So parts truck value only. Either way, you don't change the deal in the 11th hour. Not cool. All of a sudden you have someone interested and now you think you need more. To hell with that. I will rebuild the E4OD before I play that game.

Haven't pulled the codes. I have a code reader somewhere. Haven't seen it in a while. Either way I know signal is going to the TCM, just not coming out to the tach. Also truck is in limp mode till tach starts working so my thought is TCM is flaky. Starts working after it gets to a certain temp while running.

I am going to re-flow the solder joints on the TCM next. Then check again.

 

[Dirtleg]

Update. When going over the TCM before soldering I noticed there is a film capacitor, number on it is u33M63, that has let the smoke out.

In researching that part number I couldn't find anything that matched as far as form and size. So I just ordered another TCM from ebay.

Seems there are no more remans available anywhere at the moment. Rockauto had zero. All the Cardone units showed out of stock everywhere I could find that listed one. At least less than $350. And I am not willing to spend that.

 

[Nero]

Oreileys carries them, at least last year they did.

https://www.oreillyauto.com/detail/c/remanufactured/engines---transmissions/transmission---transaxle/transmission-parts/transmission-control-module/ada074969c3f/cardone-transmission-control-module/a1c0/736100/v/a/5335/automotive-truck-1993-ford-f-250?q=transmission+control+module

 

[Dirtleg]

Oreileys carries them, at least last year they did.

https://www.oreillyauto.com/detail/c/remanufactured/engines---transmissions/transmission---transaxle/transmission-parts/transmission-control-module/ada074969c3f/cardone-transmission-control-module/a1c0/736100/v/a/5335/automotive-truck-1993-ford-f-250?q=transmission+control+module

Unfortunately they do not anymore. Showed not available for pickup, not available for delivery.

They may get them back in stock at some point but currently nothing out there.

 

[Nero]

Unfortunately they do not anymore. Showed not available for pickup, not available for delivery.

They may get them back in stock at some point but currently nothing out there.

They show that for me too, but if you call sometimes they can get them still.

 

[Dirtleg]

Good to know. Should have called.

 

[Dirtleg]

Okay final note to this saga. I swapped out the TCM for a good used one. Problem solved. Works as expected.

 

[WrenchWhore]

At this point is it worth going to a stand alone unit for the E40D? Seems like when a the E40D works good people are ok with them.