Lock up solenoid

[Biggysurf]

Hi,
I own a 1992 2.4 auto. When I switch the headlight on the lock up solenoid fails to operate. Works perfectly with headlights off. I can be traverling at 60 mph in "5 th" as soon as headlights on, straight into "4 th"! Then lights off "5 th"! Have changed ECU, please help!!!

[TonyN]

Check all around the engine and behind the dash for broken earth wires.

When you say you've changed the ECU, do you mean the main one or the transmission one?

Also if its got spotlights that are wired to the headlights, check the wiring as the lights are negative switched, so if you intruduce another earth somewhere it can cause wierd things to happen.

[angelonawire]

help also required

Tony you mention a transmission ecu, is this the same for the 3.0l or is it a combined engine trans ECU.

I have recently lost overdrive lockup,(2 weeks ago) it only ever gets to 3rd gear and is revving higher than normal before it changes up, when it does change up it does so with a fair kick rather than a smooth change.

I have been towing a fair bit recently and noticed the engine temp rising (not into the red), i removed the stat, water is flowing well through radiator, so I am guessing that it is the trans fluid causing the temp rise.

now if i am driving over 50mph without a trailer, as it is only getting up to 3rd it starts to rise in temp as the revs are sitting around 3200 to achieve 50 mph

i had a sniff of the fluid and it did smell a little burnt and was pretty black/brown in colour, so I flushed through 15 litres to clean it out with 5 mile drives between each 5 litres. this didnt help

I then bought a "thoroughly tested and working" ECU off fleabay, changed that out and still no joy.

Any thoughts, I know this is a common fault but there doesnt appear to be an easy solution

the only wiring that appears a little dodgy, are the two large plugs up high on the near side of the trans box, they were taped together, and I soldered them up about 6 months ago, what are they and could this give this fault?

oh and there is nothing abnormal with dash ECT and O/D dash lights

thanks