1992 940 auto 4th gear not engaging

Richard-Bundy · Post by **Richard-Bundy** » 24 Sep 2013, 00:56

hi,
been a while since I was here.
my Sons 940 has been so good, I just got a similar one for my daughter. these cars are the best !
anyway, my sons 940 which has AW71 transmission, has recently developed a strange issue.
he and the car are 1000km ( 600 miles) away from me, so I am going by his diagnosis. apparently the lock up button on the shifter works, it lights up the arrow on the dash, and at speed the torque convertor does lock up, but the car stays in 3rd gear. that is, in normal use it starts off in first, goes thru second and third, stays in third, and eventually locks up while still in third.
from what I gather, the solenoid and relay are related to the lockup function only, so they must be ok.
any ideas ?
thanks

lummert · Post by **lummert** » 24 Sep 2013, 06:24

The relay and solenoid are only related to the overdrive lockout. But you're on the correct path. Check the relay, solenoid and the wiring.

Richard-Bundy · Post by **Richard-Bundy** » 24 Sep 2013, 14:05

thanks,
I was thinking about this as I woke up this morning ( I am down under ), and realized that the button on the shifter does 2 things, it drops the car back to third, and also cuts out the lock up function. so maybe the relay has 2 separate functions hidden inside it. and in this case its the third/forth gear side that's funny ? anyway, I will order one of those and get my son to swap it and see how it goes. I will report the result when I have one.
thanks again.

Richard-Bundy · Post by **Richard-Bundy** » 03 Mar 2014, 15:16

hi, just an update on this. the car was in storage over xmas break so I couldn't do anything.
the relay change didn't fix it, but an IPD solenoid bypass plate did.
when I took off the solenoid, the wiring at the solenoid itself appeared damaged, so that was probably the issue. therefore a new solenoid would be the 'correct' fix, but the IPD plate does the trick.
also, after putting on the plate, there was initially no improvement, but after a few miles it came good. I am guessing the passages being blocked for some time had to be blown clear.
also, the main thing here is that the button on the shifter and therefore the solenoid activate both forth gear and the lock up torque converter. so when this is faulty, you only get third, and loose two 'steps' in the transmission.

lummert · Post by **lummert** » 03 Mar 2014, 16:24

I think the converter lock-up on your trans is mechanical. Someone correct me if I'm wrong.