Well, a lot has been going on with the no start problem. Some good, some not good, and most not explainable.
We have replaced the following items: 1. Front electrical bay (start ) solenoid. 2. Ignition switch. 3. Rear start switch. 4. Comp. light switch in rear start area. 5. Solenoid located behind the battery compartment (the most inconvenient place you could ever put an item like this!) 6. New chassis batteries.
Also we have cleaned most every connection we came across although most looked to be O.K. except the rear comp light switch. Located all three Allison components (i.e Transmission shift selector pad, Transmission VIM, and main Transmission ECU). There are only two fuses total in the three components and they were 10 amps in the VIM box and both tested good. I believe these three components are functioning O.K. as I will explain later as we were eventually able to get the engine started. Also, there are four fuses in the fuse module tray which all tested good.
While doing the above listed things we began to identify and trace wires as Steve suggested previously. One of the things we discovered is that the wiring diagram that is attached to the inside of the electrical bay door is not accurate. For example, On the diagram CB22 says service board, XSMN, ECU, and VMS2. The wires connected to CB22 are actually labeled as #265 Ign Power VIM relay, #202 Ign ECU and #233 Ignition Power. Until we discovered this it made any tracing of the wires a futile effort. We finally identified the wire numbers and names on all the wires coming off he copper buses and will be tracing those as well as checking for continuity and power.
Another major problem has been getting the proper schematics. I have down loaded over 100 pages from the BAC fourm and other sources and have had no luck in finding schematics for a 2000 Patriot Thunder with the rear start feature. I realize that many of the schematics I have examined apply to more than one model of coach. For example many of the schematics are for the Marquis, some are labeled Thunder, Montery, etc. There is a lot of over lapping of applicability between the various models but the one thing that is missing from all of them is ANYTHING dealing with the rear start circuitry. If anyone has ANY information or thoughts on this please advise. The whole wiring of the rear start circuitry is confusing. For example, the rear start switch, the comp light switch, the rear oil pressure gauge which is not working, and the rear water temperature gauge which is also not working are all connected or wired together in some way. We have identified all of these wires but have not figured out how it all connects.
Now, I mentioned at the beginning that there was some good news. We finally did get it started, however, it is an on again, off again situation. Here is the time line and other details:
1. After replacing and cleaning the previously mentioned things for over 30 days and having no results, on Thursday 7/20 we started an attempt to identify and trace some wires. A the end of the day I turned the key as I usually do just to give it a try and low and behold the shift panel lit up and the engine started right up. I let it run for 10 minutes and I was able to drive a short distance and reposition the coach. Shut it off and restarted again as normal. All was well and I shut it off for the night.
2. 7/21 went out in the morning and turned the key and it started normally. Let it run for about 10 minutes and shut off. Did some more voltage checks, etc. and 3 hours later turned the key and the shift pad did not light and there was no cranking. Later in the afternoon we were again checking continuity/voltage from electrical bay to rear start switch and when I turned the key to accessory the shift panel lit up but the engine would not crank. I left the ignition switch on accessory and went to the rear start area and moved the switch to rear start and pushed the start button with no results. About 10 seconds later out of frustration I pushed the rear start button and the engine stated right up.
3. 7/22 Attempted to start from both front and back several times with no result. Transmission did not light up and engine did not crank.
4. 7/23 Attempted to start with negative results. I continued to test for voltage at rear start and wife turned ignition to accessory and the transmission pad lit up. I went up front and turned ignition to start and engine started normally. I shut engine off for a few minutes and then restarted normally. I did notice that the transmission light did blink momentarily and the "cat eyes displayed on the shift pad for 1 or 2 seconds and then went back to the normal display. The engine continued to run normally. I shut it off for a few minutes and then attempted to start with negative results. Shift pad did not light up and no crank.
5. 7/25 Went out this morning and attempted to start with negative results. No light in shift pad and no crank.
What all of this means I do not know. I do know that if the trans shift pad does not light up the engine will not start. Also that on one occasion the pad was lit up and it would not start from the front but on that occasion it did start from the back. I am leaning towards the problem being a bad/weak ground or frayed wire somewhere. Today we are tracing wires and checking continuity. Also I am replacing the relay in the fuse module tray although it may be O.K. Also I'm not sure about the factory label affixed to the battery bay door which lists the components of the fuse module tray as ECM Relay which is a 15 amp fuse, XSMN VIM 20 amp fuse, Service center 20 amp fuse, Event recorder 20 amp fuse, and an actual siemens relay labeled as ECMR. I assume the one labeled as "ECM Relay" is the 15 amp fuse and is not itself a relay but puts power to the ECM relay. After seeing the labeling on the electrical bay door I'm not sure what to make of this. One other thing, I would like to check the wiring to the back of the fuse module tray to check for corrosion but can't figure out how to access it. No screws are visible to take it apart.
This is a lot of information to digest but it is what it is. Not a simple problem to diagnose but am still hoping for a simple solution.
Any thoughts or ideas are welcome.
Tom