Just come across your site. layout is very similar to WWW.hiluxsurf here in the uk.

I have a 3.0L surf that will not go into top gear. She's had a full service and at the latest auto electician reckons that possibly thermostat cable from engine block to gearbox is faulty.
Thing is that he could not find it.
Any ideas anyone?
He says that this is simple option befors having to go into gearbox housing.

 

What year? 4WD or 2WD? I am assuming you have an electronic controlled automatic transmission and it's not going into OD right? If so, I would guess the engine coolant temp sensor may be the problem. Here is a link to the 93 FSM http://personal.utulsa.edu/~nathan-b...fsm/index.html Let us know what you find out.

Also possible that your thermostat is stuck open not allowing the coolant temp to get high enough to trigger the sensor. Is the coolant getting up to normal temp?

Here: http://personal.utulsa.edu/~nathan-b...20electron.pdf scoll down to page 2 of 11 shows the engine coolant temp sensor right behind the throttle position sensor. Your's may be reversed if you have left hand drive over there.

Here are a bunch of tests if you have a multimeter: http://personal.utulsa.edu/~nathan-b...34electron.pdf scoll down to page 6 of 13 (for 4WD)

 

You link to the site doesn't work.

Anyway, here is the test for the coolant sensor:
http://personal.utulsa.edu/~nathan-b...98engineco.pdf
Also could be a solenoid preventing it from top gear (assuming you mean overdrive).
Test the coolant sensor first then the solenoids.

MT_goat......thanks for hosting those!

 

Try: www.hiluxsurf.co.uk

 

I don't know who is hosting those but it's not me. Sure is nice of someone though, thanks.

 

Be sure and note the precaution at the top of this link before doing any tests on the back of the ECM. http://personal.utulsa.edu/~nathan-b...20electron.pdf

I would wear one of those wrist straps that ground your body to prevent static damage to the ECM.