Transmission going into limp mode

[Spetz]

Hi guys,

I have a 2003 Diamante with a 5 speed auto transmission.

While towing a heavy load, it went into limp mode.
After that it drove ok for about 20 miles, then started going into limp mode each time I drive it,

Limp mode would kick in while reaching 30ish mph at first, but now it goes into limp mode at anything between 15 and 30mph.

It goes into limp mode regardless of what gear it's in.

I have reset the TCM, swapped the TCM relay, checked and cleaned all connectors.
I have drained the ATF and checked for metal debris, including on the magnetic sump plug. All clear.

I have extracted these error codes:
42 Short Solenoid No. 1 Circuit
43 Open Solenoid No. 2 Circuit

Two solenoids going off at the same time seems unlikely.

Anyone know what it could be?

 

[ctechbob]

Sounds like it is time to dig up a wiring diagram and test the solenoids. Should be simple enough (As long as the failure isn't intermittent) if you can get to the wires that go to them. They should read a certain amount of resistance, if it is below the factory spec, then the computer will read it as a fault.

 

[Barkleymut]

How much weight were you towing? Going up any hills/mountains?

 

[Spetz]

Hi guys,

I checked the Mitsubishi procedure and the 2 codes are for 2nd and 3rd gear speeds not synchronizing (input shaft and output shaft speed not as expected).

According to the workshop manual, if the input shaft sensor and output shaft sensor are working fine (I will test this today) then it is an issue with the "underdrive clutch".

What does this do exactly?
And if it were faulty, would the transmission make any noise or give any signs of issues? As the only issues for me is going into limp mode.


I was towing a heavy load (more than the car is rated for) but driving gently on a flat road.
However the trailer was "porpoising", so causing a lot of jerkiness, and I am worried this jerkiness is what might have caused the issue