My stupid impulse buying has landed my with a TF Altera LS. Now the transmission is displaying a few faults, when i got it i was told its stuck in 3rd - which was true, although no Neutral light flashing (which I thought it would do considering its in limp mode).

Disconnected and Reconnected the battery, which made it shift through the gears fine for a while, then it do all sorts of interesting/annoying things, such as stay in 1st for 3-4 seconds after it should of changed, stay in 4th after slowing down to go around corners etc.

My initial thought was just to change the box, but I've noticed the heater core is leaking, there is residue all over the ECU, and there's no plastic cover - which my TJ has.

So would it be a plausible idea that it could be the ECU playing up due to moisture?
And would a TE Exec 3ltr ECU plug in fine?
Too my understanding there's no need to match ECU and BCM in the pre TF's?

Te,f have no bem however have immob.

Te ecu and tcu are different

You need to match numbers off ecu but first try cleaning connectors etc on the ecu

as above, cleaning the connectors on the ecu will be a cheaper way to test it, just buy a can of electrical cleaner for $12, pull the connectors on the ecu and spray away, while the connectors are still damp, plug it in and unplug it a few times as well. this will loosen any lime scale on the connectors

Te,f have no bem however have immob.

Te ecu and tcu are different

You need to match numbers off ecu but first try cleaning connectors etc on the ecu


Cleaned out the connectors on the ECU and the plugs today, man there were filthy!

Alas no change in the transmission's behavior, so tonight I've started to replace the box with one i have here. I'll see how it goes and post back/

Update!

But.. Theirs only bad news.

Changed the gearbox today, with one i know is good (have driven the car it came out of), refilled with genuine Mitsubishi fluid.
And there's no change whatsoever.
It is fine until operating temperature, then flares up, then harshly drops into limp mode.
If i turn it off, and start it after a minute or two, its fine for the first few shifts it has to do.
Thinking it was the ECU, I changed it out of a TE, with no luck, still the same symptoms.
Any other ideas folks? I think I'm over the whole guessing game .

"It is fine until operating temperature, then flares up, then harshly drops into limp mode." That sounds like a sensor problem, had the same with a cam angle sensor - only acted up when warm.

I suppose reading the error codes is out of the question? If it isn't the trans, or the ECU, must be an engine sensor. In that case, reading error codes should help. If you get nothing, check gearbox sensor wiring and connections.

(I have of late become a convert to reading the error codes first, when a problem pops up.)

Did think of it being an engine sensor, but the only one i could think of that would have anything to do with it is the TPS, which i changed to no avail...

Error codes. Retrieve them. Learn from them.

The transmission has an oil temperature sensor. If the TCU gets an out-of-range oil temp then it will drop into limp mode. I'm presuming that when you changed boxes you didn't change sensors; that being the case it might be worth checking the state of the harness (continuity/resistance) between the sensor & ECU, as wire damage may be affecting the sensor signal seen by the TCU.

With the ignition on, the Neutral indicator lamp in the cluster should blink at 2 flashes a second if the oil temperature is too high; 1 flash a second if there's some other problem known to the TCU. If the Neutral lamp is blinking there are retrievable error codes.

When i changed the box, i changed the whole lot, sensors and all. I know for a fact that the box was fine in its previous car, and same thing with the ecu

When i changed the box, i changed the whole lot, sensors and all. I know for a fact that the box was fine in its previous car, and same thing with the ecu


Sorry, I wasn't clear - I meant that I presumed you didn't swap sensors between the boxes. You have done what I presumed you would have done. That being the case the temp sensor issue, if that's what it is, will be harness related rather than ECU or sensor related as both ECU and sensor have been changed without changing the behaviour.

Sorry, I wasn't clear - I meant that I presumed you didn't swap sensors between the boxes. You have done what I presumed you would have done. That being the case the temp sensor issue, if that's what it is, will be harness related rather than ECU or sensor related as both ECU and sensor have been changed without changing the behaviour.

Hmm,
Well I've just cleaned out the ECU plugs with paint thinner (had some laying around), the issue stopped for a while, but then eventually came back. I'm contemplating cutting the plugs off and soldering new ones on, but that is a last resort
Tomorrow i intend to get some proper contact cleaner and give that a go. This is odd because the ECU plugs looked tidy.

Well,
Its fixed! I think..

Spray a can full of contact cleaner in the ECU plugs this morning, was good for a 20 k drive and then bam back in limp mode.

So, got keen and cut all the ecu plugs off, and solder + heatshrinked all the joins.
Just came back from a 200k drive, and its all good.

So touch wood, but i think it might survive.

i have this same problem and was wondering if this worked. and id like more detailed information. thanks