Replace transmission or buy a new truck

I have a 2010 4.6L v8 250k Crewmax. My check engine light indicates D solenoid is not working. A local, reputable tranny shop says the solenoid is ok, but it’s the wiring or computer— told me to take to a reputable Toyota specialist— the master Toyota mechanic says solenoid D is showing an open circuit and that I need a new tranny, and should also get the torque converter replaced —6k for both. Dealership is 5400 tranny alone. Tranny shop says it’s not the tranny. I’ve done some maintenance on this truck and she runs great, other than this. Can y’all give me some advice.

also, are all trannys rebuilds?

 

How much do you trust the tranny shop? I have a local shop that has earned my trust, but it took a lot of good references that I know personally to do it, then a couple of very positive experiences with them. I would try to find a known, very good tranny shop for another opinion if you don't already have a lot of trust in yours. I've been misled enough by Toyota dealerships that I don't trust anything they say without a good second opinion.

 

Even in the worst case scenario of needing the trans replaced I would probably do it if you still love the truck, and it’s in otherwise good condition. It’s especially easier to justify at the moment with values so high.

 

What about LKQ low mileage trans?

 

I believe in starting small, using the simple approach and working your way up from there.

Would a new computer module fix it? Who knows,but if it saved you thousands would t you want to see if it helps first?

 

It would be a real muthaf%*ker to have the dealership put in a new transmission only to discover that the signal for D solenoid just isn't getting there.

The transmission shop should be able to look for the signal for the D solenoid both coming out of the TCM and at the plug for the transmission. I would suggest offering to pay for them to complete this diagnosis.

You can replace the entire valve body with the transmission still in the truck BTW. But if you have a control issue that would need to be fixed anyway.

 

Depending on your trans shop and how much you trust them, I don't see a reason to steer you in the wrong direction. If what the toyota specialist said is true, it could very well just be a wire somewhere that a mouse or something chewed through.
I had a Pontiac that had an issue with the o2 sensor that after being replaced still showed a code.
Turned out a wire was somehow screwed up somewhere in the loom. I ran a new wire to it and fixed it in a few hours after a headache of trying to figure out what's wrong with it.

 

Welcome from NY.

I would change the D solenoid first.

 

I tend to believe the transmission shop when they say that the solenoid is OK. What the fault code means is that there is an beak in the electrical circuit for solenoid D, which is the solenoid itself, the internal wiring harness inside the transmission (including connectors), the external wiring harness(es) to the ECU (also including connectors) and the ECU itself (unlikely IMHO)

I’m assuming that the Toyota “master tech” (snicker) only read the fault code and failed to diagnose the exact part of the open circuit with an ohm meter. It sounds to me like the transmission shop tested the solenoid resistance with an ohm meter and found it to be within spec. At that point, they determined that the problem was outside of the scope of their work.

If my assumptions are correct, a replacing the transmission and torque convertor won’t solve the problem unless the internal wiring harness is the problem. And buying a reman transmission instead of just the internal harness is the opposite of cost effective.

Most likely the issue is a broken / rubbed and corroded out wire in the external harness, or a corroded connector.