Tranny 01' Highlander

[John_T]

2001 V6 2wd

Problem: P0770 Shift Solenoid E Malfunction

Task: Drain fluid, drop pan, drop screen, disconnect harness, drop valve body

Next: Red & Black solenoids read 13ohms. 12v Bench test opens and closes valves.

Next: Help identifying large cylinder solenoids (w/yellow connectors). What are they? How do you read current? How to bench test?

Any help is appreciated. Any diagrams or *pdf's showing assembly and valve body going back in would be helpful. Thanks!

[shall36]

The documentation I have is for a different trans unit, but here's some general advice. I don't know which is which, but the solenoids control gear changes, converter lockup, and overdrive activation.

If you have a shift problem that might be linked with a solenoid, remember that the solenoid controls the flow of fluid through specific passages. The ECU tells the solenoid to activate (First possible failure). The Solenoid can only activate if the solenoid coil is working. Usually, an ohm test will identify an open (failed) coil (Second possible failure). The solenoid can be activated by the ECU and functioning properly only to have the passage plugged with debris (third possible failure).

As for activating the solenoids, I believe that you would need a scan tool (probably Toyota specific) to tell the computer to activate each solenoid. If you were able to do that, you would hear the solenoid click. You could also put a volt meter on the wiring harness to measure for voltage. Probably no need to measure current. If you have voltage and you have resistance at the coil, you will have current flow.

In your position, I would just ohm out each solenoid and even ohm out the wiring harness going to each solenoid. For the later, you'll need a good wiring diagram. The idea is to trace the wiring back to the ECU and make sure that the wiring for each solenoid is intact. If you find a solenoid that has open resistance, the solenoid is bad.

Good luck!

[ddvk]

If you have gotten the Valve Body off the tranny, then it is a pretty simple to replace. The solenoid pack would usually be a pack of four, when you replace them be sure to get new o-ring(s) installed too.

How many miles and what is the PM on the tranny you have done so far?

Correction : I meant valve body and not TB.

[John_T]

Thanks for the responses!

Here's where i'm at:

Thanks to this forum, I learned how to access the TIS library for the day and that got the documentation I needed. Thanks!

For P0770 on the Highlander, the spec calls for two tests on the DSL solenoid:
1. apply 12v current to confirm operation.
2. blow 71psi into it to make sure it doesn't leak.
We passed both tests.

Next, the spec says to inspect valve body for any cracks or obvious malfunctions. We passed that too.

Next, we reinstalled the assembly, put the pan back on with a new gasket, refilled tranny to the proper level, reset the P0770 code and went for a 15 mile test run.

After she warmed up to operating temps (10 mi.) we brought her up passed 50mph and carefully viewed the tach for the 100-200 rpm drop for lock up. Nope, not there.

Brought her home, checked for pending code - yup, P0770 pending.

Okay, the next step on the spec says check torque converter auto-clutch. So, I guess this weekend we'll drop the trans-axle, pull converter off and do as the spec suggests:

Clutch should spin free one way, but lock going the opposite way. I expect to find it not locking. Anyone know what $ the auto clutch assembly goes for?

[John_T]

Been a while but the Highlander just came back from replacement of the torque converter and a transmission rebuild. Upon receiving the SUV back we’ve noticed two issues we’re trying to figure out:

• Some kind of vibration and drive train turbulence which comes and goes during normal low rpm driving. It’s not like it’s a big deal, but it’s kind of annoying as it wasn’t like that before, so we’re puzzled about it.

• Drive train seems smoother but not as strong.

The job itself was delayed due to the transmission not shifting properly into third gear. The SUV was brought to Toyota to re-program that part of the computer which controls gear changes and here’s where things got weird.

It’s an early 01’ Highlander and the Toyota Dealers diagnostics identified the VIN as the 4-cyl with a different transmission. So they supposedly reprogrammed the entire computer to be what it is, a V6 with the right transmission.

Anyone ever hear of that? Could the engine feel off because the computer is different? The transmission meanwhile, feels great. It shifts perfectly and seems better than before.