TLAV transmission won't upshift from 1st

[Malcolm Towrie]

We (Ontario Regiment Museum) have acquired a TLAV. It has a Allison X200-4B transmission with is modern enough to be controlled by an electronic transmission control module. It won't shift out of first gear. The fluid level is ok.

I know from having problems with modern automotive transmissions that the TCM diagnostics are usually very good, so I think our first step should be to find someone with a scanner we can borrow to see if there are any codes stored. We'll be calling around but I wondered if anyone on here knows if army repair shops typically have these scanners in their toolkits?

Malcolm

[Robin Craig]

Malcolm, on your behalf I have copied and pasted your posting into a few of the Facebook groups. I have your email so will cut and paste back whatever results come in.

[Paul Singleton]

Although I am not familiar with this particular model of Allison trans if the output speed sensor signal is lost the trans will not upshift. The on road trans also uses this signal for the speedometer. Also metal particles may be present on the sensor itself, causing a poor signal. If the sensor is accessible you may be able to test it with a multimeter and see if there is a voltage signal when moving.

Paul

[maple_leaf_eh]

There are TLAVs in CF service. How about asking the Fleet Manager for a copy of the technical bulletins issued for NSN 1234-21-asdfa-afafds between date 1 and date 2?

If there is reluctance to share collegially, for $5 any Canadian can do an Access to Information request based on exactly those selection criteria.

[Malcolm Towrie]

Thank you, Robin. As you know, I have been contacted by one of your contacts who may be able to help.

Malcolm

[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