Is this another Norway car Jetboy?
What I am going to say will be bad news financially, but as he bought the car with the transmission fault, he may be expecting that it will cost money to fix it properly.
I suspect the reason the car is not engaging with 4 is a sticking valve or a servo problem, and the gearbox may need to come out and be refurbished.
When I got my first SVX, a '91 JDM car, I drove it for nearly two years with only gears 1-3 working. [
I am not suggesting your friend keeps driving the car with only three gears, he may not be as lucky as me and the car would strand him somewhere] I got the gearbox re-built and new clutches put in, it remained perfect from then until I sold it years later.
The ATSG troubleshooting chart suggest the following for no shift 3-4 on the 4EAT, in order of frequency:
On-car checks:
3) Faulty control unit [TCU]
23) Valve sticking
16) Faulty ATF temperature sensor
Unit check [aka gearbox out]:
47) [Brake] Band and servo slippage
I am labouring the obvious because your first language is not English, but the on-car checks can be done without taking the gearbox from the car. As follows:
Faulty TCU: simplest plan is stick in a TCU from a known good car; if the problem is solved [and assuming the wiring loom is not damaged] then you know what you need is a good TCU and don't need to strip and rebuild the box.
Valve sticking: the reason this can be checked on the car is you can drop the transmission sump and remove the cassette with the valves and fix the relevant sticking valve. Re-install the cassette, fill up with fresh oil and away you go, assuming a sticking valve was your problem.
Faulty ATF temperature sensor: This one is obvious; if the sensor is faulty and the TCU is only registering a temperature that is incorrect and too low, then the TCU will not allow 4 range to be selected. The objective of this temperature control is to allow the oil in the gearbox to reach the correct higher temperatures through maintaining the higher revs of the lower range gears. If the TCU is not getting the correct expected higher temperature registered by the [faulty] sensor, then the TCU will not allow 4 to be activated and also will not allow lock-up to happen.
It would be very wise to thoroughly investigate these three possible faults before taking the gearbox out for the fourth suggestion.
And speaking of that investigation is your friend sure that the "transmission specialists" you are using know enough about the 4EAT to fix this problem?
The last suspected failure with the gearbox removed: [
unit check in ATSG speak]
Band and servo slippage: Personally I would suspect the servo in this case because when the band is loose you also get problems with 2 range, they are both on the same band [ranges 2 and 4], and you do not report fault with 2 range.
When and if you have the gearbox [transmission] out of the car the guys will not be repairing one servo or one band or one clutch. Once the box is out it is usual to rebuild all wear and tear parts and check the operation of all valves etc. That's what makes it so expensive, but is the correct procedure.
This makes it all the more important to check the other faults out thoroughly while the gearbox is still on the car; if you manage to determine it is one of the three suggested faults above, you will save yourself a lot of money.
So make sure your transmission guys know what they are doing.
Sorry for the long post [guys round here prefer 2-line responses
] Best of luck with it.
Joe
