TLAV transmission won't upshift from 1st

[Malcolm Towrie]

Good info , Paul. Thanks. It would be easier to find the diagnostic port and borrow a scanner to monitor the speed sensor and look for codes, but if that doesn't pan out, we'll need to track down the speed sensor and I have an automotive oscilloscope we can use to check it out.

We'll check if the speedo has quit also.

One of the mechanics working here just told me his shop has a scanner for road-going Allison trannies. The TLAV has a specific military model of transmission but if it has the round 9-pin diagnostic port, we may be able to at least read the codes.

Malcolm

[Malcolm Towrie]

Thanks, Terry. There are people here trying to get a manual. We just got the TLAV a couple of weeks ago, so we'll see how they get on.

This is quite a modern, sophisticated transmission, released in 1999. Maybe the documentation is still restricted?

Malcolm

[Aide Memoire]

Tried to get documentation for ours and everything of any use is not-for-release as per the red-indicated stuff att'd.

[Malcolm Towrie]

Thanks, aide. That's what I've been finding. But we've got some leads.

Malcolm

[Malcolm Towrie]

We got a manual and it turns out I was wrong, the 6V53 turbo engine is ECM controlled but the transmission is still mechanically controlled, i.e. no computer involved.
Unusually, for Canadian TLAV's, the throttle valve is not regulated by the throttle pedal position but is fixed, so TV pressure does not vary.
I adjusted the TV pressure down a bit from 110 psi to 100 psi and we got the shifting back. Although all is not still not well in my opinion.

Malcolm