[David and Teresa]

Hello all,

I've been working on this problem for a couple month's. Basically, the Allison Shift Pad doesn't light. The coach cranks anyway, but will not go in gear. It will actually crank without the shift pad connected.

I've had Allison mobile repair out 3 times. The first time, after checking wiring from the computer to the shift pad, voltages, etc., they said it was faulty shift pad. I ordered a rebuilt replacement. No lights.

The second time, more continuity checks and they programmed a brand new, in the box computer, and brought it. We swapped out the computer, no lights. I called the Allison Tech line and talked to Mike, a WTEC II guru, in fact, the only one there. He gave me a couple of things to try and then call him back.

On the third visit, Mike suggested we power the shifter directly from the battery. We ran lines from back to front, powering the shift pad directly. No lights. Also, we made a 12vlLight with a couple leads to make sure it burned bright when checking power wires. All the wiring at the front of the coach appears fine. 

I called Mike back at Allison to report the findings, and Mike retired last week. Mike was the only WTEC II tech there since they don't support II any more.

So, the only thing I haven't done is check the continuity from the transmission to the computer, which I was hoping I wouldn't have to do. Any ideas? Is it possible that I have 2 faulty shift pads?

Thanks in advance for any insight.

David

[Richard]

Sorry to be so dense. Is it safe to say that there are no lights on the keypad at the top, meaning the little green indicators are darK?

I only ask because there is the shift inhibit circuit that will not let the Allison go into gear, that is tied into the HWH room controls. Most Newells have a switch override on the HWH control box to keep this from stranding you. Just for giggles, have you tried that switch in both positions?

Obviously, the computer and keypad connections have been unplugged, cleaned, and replugged. Have you tried the same with the connectors on the transmission?

I would try these couple of simple steps before I started ringing out the connections from the front to the transmission.

[David and Teresa]

Hey Richard,

No, the shift pad is completely dark. I know about the HWH bypass (learned the hard way). And the Allison tech checked and cleaned all the front connections. My next move is to check continuity from the transmission forward.

The Allison tech said you can check the shift pad by taking it to the battery and connect pins 1 and 6 to positive and pin 7 to negative. It should lite up, but it doesn't. Neither does the rebuilt shift pad I ordered.

Do you know of a way to check and see if the shift pads are OK?

Also, I contacted Newell first and we went as far as their knowledge could take us. When they had no idea, I made the call to have Allison come out.

[Richard]

Thanks for the clarification. I wish I knew more Allison specifics, but I can only help with general problem solving and you have done a lot.

The fact the 2nd pad won’t light up when “hot” wired is very concerning. Before drawing any conclusions, your reference to PIN numbers doesn’t jive with the Allison schematics I have seen on line, which have Alphabetic designators. I am probably not finding the right schematic. My point is that the schematics for the shifter probably need to be confirmed on the 12V inputs before concluding both will not light up.

In my own shenanigans, when I get “lost” in problem solving, I find it’s time to go back and confirm what I think I know.

I have found a bunch of threads on the interweb about the Allision pad not lighting up. All of the ones I have read were all power to the system caused. Your test light to the front was a GREAT way of confirming you had power.

In the three visits by the Allison techs, is it correct the only shift pads tried were your original and the rebuilt replacement? None of the Allision techs had a test shifter to evaluate?

If we were close, I would yank my shift pad and bring it over.

[Johnnyboy]

Do you have one of these boxes. There are some fuses and relays inside. Check carefully. I had a blown fuse. Fixed my problem

[David and Teresa]

I have all the wiring schematics (the Allison tech printed them out for me). Pin 6 on the shift pad is a "wake up" wire. Pins 1 and 7 are hot all the time in the shift pad, and voltage to 6 wakes up the shifter. This is confirmed by the mobile tech and Allison on line. The other two connectors that work on the pad are communication from the computer.

You don't want to take your shift pad out. I had to call Newell and it is quite a task.

The local Allison dealer doesn't have a new, or old shift pad. They can order one in (at over $3k).

---

Do you have one of these boxes. There are some fuses and relays inside. Check carefully. I had a blown fuse. Fixed my problem

Yes, that was the first thing the tech checked. The two fuses are good. The six relays are all the same. He took them out and measured each one. All good. Then we placed them all in different locations as a second test.

[encantotom]

i am with richard on this one with an addition.

first it seems really strange that 2 keyboards would be dead. possible, but doesnt seem likely. like richard mentioned, confirm that you really have the right schematics.

second, is like has been said, all the internet searches talk about dead keypad as power. does the power come from the relays in the control box? one person had a bad relay. you said you swapped them around. how many are inside it?

is there any fuses between the batteries in the back and the control box?

tom

[David and Teresa]

i am with richard on this one with an addition. 

first it seems really strange that 2 keyboards would be dead.  possible, but doesnt seem likely.  like richard mentioned, confirm that you really have the right schematics.

second, is like has been said, all the internet searches talk about dead keypad as power.  does the power come from the relays in the control box?  one person had a bad relay.  you said you swapped them around.  how many are inside it?

is there any fuses between the batteries in the back and the control box?

tom

Allison printed the schematics. They are correct. Power the shift pad
 comes from the control box with the relays. There are 6 or 8 of them in there. All checked by Allison. However, as I noted, Allison had us power the shift pad directly from the batteries at the back of the coach as a test. We did.

[Jack Houpe]

I would start reading the wires out going to the control panel from the relay fuse box, if there is 12v present then there is a ground missing somewhere. If you can't power up directly from a 12v battery your problem is in that panel or plug going to the panel. Both panels being dead is very strange.

[Richard]

David,

I am not trying to nit pick your words, I truly am trying to help find a needle in a haystack with you. Keeping in mind that us armchair quarterbacks are no better than the on site info provided by the poster’

You have made two statements which seem to be in conflict to me. taking it to the battery and connect pins 1 and 6 to positive and pin 7 to negative AND Pins 1 and 7 are hot all the time in the shift pad, and voltage to 6 wakes up the shifter. Is pin 7 supposed to be connected to 12V positive or negative. The Allison schematics I have been looking at show two negative connections through the VIM box.

Can you snap a photo of the schematic and post it? There a handful of Electrical Engineers in our midst, let’s put them to work………………