[Archived]

Hey Mike,

On My 96 XL the Allison ECU is tied into the DDEC for the S60. There is a white box in drivers compartment bay where they are tied together. The Techs at a Detroit / Allison service center recently had access to the DDEC and Allison ECU through the diagnostics plug located behind the drivers seat on the port wall near the carpet. It took Detroit / Allison software on a laptop to gain access to the information on My coach. Two different techs hooked up laptops to it. One that specialized in Detroit, And the other who specialized in Allison. The Tranny guy diagnosed a problem with the jake brake. After the engine guy could not fix it after 6-8 Hrs. Then located a wiring problem that fixed the jake. He also re-set My shift parameters which helped with a rough shift from 3-4th gear. There might be another Allison access plug in the rear, But in My case they accessed the Allison thru the DDEC port.

Safe travels,

Rocky

[Kirby]

When Prevost started using the Allison World Transmission they used the VIM box from Allison. This box contained two fuses and 6 relays. At the end of the 90s and with the XL2 the VIM was removed and replaced by 6 relays and two fuses as part of the front electrical junction box.

So if you look in the electrical junction box you will find these relays mounted together and labeled: VIM N, VIM R, and VIM 1-4. The two fuses, F1 and F2, are mounted in the snall fuse panel in that same compartment.

The relays are wired so that most need a ground signal to activate and those grounds come from the transmission ECU. What goes through the then closed contacts of the relay may be voltage or a ground depending upon that particlular circuit.