auto trans with b&m shifter, goes to neutral instead of 4th

[Cirus_93TSI]

im trying to help figure out the last couple of issues with my friends new 1g, aside from me needing to finish tuning it, the only major problem is the shifter and/or the trans. so heres the details.

he bought a very nice 1g shell, caged with an a1000 pump for a good price, but it has an automatic trans, which has had the engine and turbo set up from his wrecked 5 speed car swapped into it and is running and driving.

the car came with a b&m ratchet shifter mated to its auto trans, to my understanding its been set up to completely replace the tcu. it requires manual shifting through its 4 gears, there is no "drive" that will shift through its gears automatically like a stock auto trans. 1st, 2nd, 3rd with the shifter, then the overdrive switch is flipped to engage 4th. this is how the previous owner of the shell ran the car.

the problem is that 4th will not engage. 1st through 3rd work perfectly, but when the overdrive switch is flipped to engage 4th, it instead drops to neutral.

anyone have any insight into what the problem is? all iv been able to come up with from my searches is people with stock auto transmissions having trouble with overdrive from burnt out end clutches, but i cant find any info on a shifter set up like this. id rather not pull the end clutch housing apart to check it because i dont feel like this is likely to be the problem, but thats our only step to take next if i cant get some input from others with a set up like this.

anyone have any ideas on whats going on here? this is the first auto dsm iv dealt with and i really dont have any experience at all with a shifter set up like this.

 

[96 420a-t]

Isn't o.d. controlled by a button?

 

[Cirus_93TSI]

yes, and with the b&m ratchet shifter, that button has been replaced by a toggle switch.
but unlike a stock automatic trans set up, this has been modified to only function by manually changing gears. if you put the trans in what would normally be "D", it shifts directly to third. the only way to engage 1st gear is to shift down to "1", and the only way to engage 2nd gear is to move the ratchet shifter to "2". if you leave the trans in what should be "D", it will never shift from 3rd to 4th gear. if you try and come to a stop in "D"(drive), the car will never shift out of 3rd gear and stall, try to start in "D" off a stop, and it will drop the rpm too low and stall. the way i understand this set up, the TCU (trans control unit) has been completely removed and replaced by this odd set up. i could be wrong about the tcu being completly gone, but in any case a large portion of the stock auto trans set up has been removed and replaced by this set up.
keep in mind this shell was a track car with a roll cage, fuel cell w/ an a1000 pump, thats been heavily modified.


based on the way the previous owner of the shell had this set up with his engine in the shell, turning the overdrive toggle switch on while in 3rd gear (or what used to bee "D") should engage 4th gear.

the problem is when the overdrive switch is flipped on, the trans goes directly to neutral, when its turned off, it goes right back to 3rd.

after looking around a bit, the wiring is set up exactly like the diagram on kigglyracing.com tech section, for a full manual control of an auto trans, with the TCU completely eliminated.
just the switch for 4th gear does not work right, just goes right to neutral.

 

[rbwtrans]

Remove the end cover on the trans and see if the OD clutches are fried. Super simple to fix if that's the case.