BAC Forum
General Boards => Technical Support => Topic started by: Jim Hosler on February 03, 2024, 09:32:52 PM
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So, this is a fun one (sarcastic) another ghost in the machine. So, been trying to get my coach to the body shop. Starts fine, replaced the chassis batteries, upgraded the generator to have its own battery (removed right now). The 07 Beaver Patriot Thunder has a #4 hot wire from the front to the back of the coach is not enough to allow a remote start of the generator due to voltage capacity of the wire (known issue from techs).
So, I start the coach and it runs for awhile (sitting) has no issues. Start driving and after a few it then drops out sometimes sputters and restarts, or sometimes it drops out and stalls. coach has no engine lights, the engine coms alarm comes up and goes away. Started the generator (had to use battery boost to get it to start) let it run for awhile drove the coach with it running no issues.
Messed around and troubleshot and found if the generator is running with power up front of the coach everything works great. So, my question and thought is do I need to replace the wire from the back panel to the front panel with #2 wire as I must either have a short or the wire is bad. Could this be a front solenoid issue? Also, my chassis solar fuse in R7 (rear fuse box) keeps blowing so I have no solar to my chassis batteries. Cable is about $900 for 100 feet so I have plenty of extra for additional connections if needed. Several questions here I know but am frustrated trying to figure this ghost out.
Thanks!
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If engine runs when gen runs, I'd check your engine alternator first.
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The engine runs in idle no issue, batteries show a charge with the Altinator gauge showing 14 plus. It also, shows in the Akkadian that the house batteries are charging off the motor.
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Jim
With the engine running at ldle.and gen set shut down and heater blower motor on high and headlights on to load the circuit ,use a voltmeter to check between a good ground and one side and then the other of the ignition solenoid there should be battery voltage present with a maximum volt drop of 1 volt from battery voltage .
I suspect are experiencing a volt drop issue in the main battery feed to the front run box or across the ignition solenoid internally ( common issue ).
If you suspect the ignition solenoid is dropping out use one lead of a set of booster cables to jump across the large solenoid terminals to see if you problem goes away.
Let us know what you find.
Eric
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Will do on the update. Just got it in the shop for a panel repair and repaint. Should have it back in 3-4 weeks. I think we are going to pull the cable either way, and now will do the voltage test on the solenoid as well. I am assuming it is in the rear cabinet where the Big Boy Solenoid is and connects to the front? I have pulled the schematics from the support page.
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The solenoid is in the “front run box”, i.e. “electrical bay”, the streetside forwardmost bay where most 12 volt common chassis-related connections such as circuit breakers, relays, and terminal busses are. Large 12v fuses are in the rear box with the “Big Boy”.
The solenoid is obvious, bottom center of the board in the electrical bay. As Eric notes, it is a common ignition system issue culprit on all models. The contacts inside can carbon up or otherwise fail to pass adequate voltage through from left to right posts. His jumper suggestion is a good one. And/or check voltage on left post compared to right with the ignition key off and then on.
There is an electronic alternative to this continuous duty solenoid, and it eliminates such issues, but it’s considerably more expensive. Most of us simply carry a spare solenoid; it’s easy to change out.
Attached see my Monterey arrangement, which will be similar but not identical to yours.
Joel
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Jim,
I think the starter solenoid on your 2007 chassis is in the rear run box. See pages 113-114 of the 2007 Patriot wiring diagrams in Coach Assist. It's the 100A solenoid if I'm correct.
Steve
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UPDATE:
Coach is out of the paint shop. Changed the solenoid. worked for a day went to leave on a trip and shutting down again. Towed to a shop. Shop says it running fine as the problem is intermittent. They are using my spare set of Keys. Could this be an ignition problem?
Engine starts runs for a short period or for a time then shuts down. Just before shut down Low battery alarm and then an engine com alarm. The ECm has been checked.
>:( :-[
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Also, Solenoid is in the rear box and is a 100 amp. Replaced with a 100 Amp 65 continuous duty Marine grade from West Marine.
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Alternator putting out?
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Jim
Does the coach restart a mediately after it shuts down or does it take some time to resolve itself?
I still suspect you are loosing power/voltage at the front ignition solenoid ( possibly a connection on the feed cable running from the chassis batteries to or from the rear run box to the front ignition solenoid) check the battery disconnect , then the power to the rear run box following the path from battery to front run box and ignition solenoid.
Use the schematic on page 79 of the 2007 Patriot wiring diagrams in coach assist to help you trace the power path.
You need to catch this when it won't start to find where the problem is ( I suspect you have a bad connection somewhere along this high current path heating up and giving you the intermittent shut down ) look for discoloured connections .
There are also a couple of things to check as well 1 being the battery disconnect another the large breaker just to the left of the big boy solenoid in the rear run box .
Hope this helps
Eric
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Jim,
Do you have a lot of keys on the ring with the ignition key? If so, suggest you remove them and just have the ignition key only in the ignition switch slot. The weight of multiple keys can cause the ignition switch to fail intermittently.
Steve
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Jim
Earlier you stated you had a separate battery installed for the gen set but it's not in place right now .
Your symptoms point to 12 volt lost to both the gen set and the front run box .
Where is that gen battery located? I assume it's somewhere near the gen set . Is the gen set at the front of the coach or side.
If that separate gen set battery is connected in parallel with the power cable coming from the back of the coach it could help maintain the voltage at the gen set and the front run box .
If this is the case it points to a fault or failure of the main power cable from the rear of the coach to the run box and gen set
Most likely a bad connection or wire (corrosion in the wire or connections)
Hope this helps
Eric
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Ok, so here is where we are today. 06/11/24
1. The Mechanic has checked all of the connections and ECM and has found no faults in the starting system.
2. The coach is running fine now (of Course but the ISO light stays lit and only goes off when we shut the batteries off.) (Big Boy combiner) not sure if this is part of the issue.
3. I gave them my set of Keys with all of the Keys on it and they are using them. (Still running) Although they have checked the ignition and it looks to be good. It is the old GM style with no chip.
4. They did the ECM check and ran it with the harness splitter and no faults found.
5. Check all of the ignition- no faults found. The front battery is switched off to eliminate from the process of diagnosis.
6. All, the front does not lose power. The dash alarms low battery, engine Comm fail and the engine just shuts off.
7. The engine most of the time stays in Comm fail and then is able to restart and then shuts down after 30 seconds to 2 minutes. If the engine shuts off and you try to restart it right away without allowing 30 or 40 seconds of time it will not restart and just keeps turning over.
8. The front run box does not have a solenoid or engine command parts in it. That is all in the rear box.
Next actions-
Tech is going to
1. check the grounds for the ECM and engine clean and secure (at my request)
2. We did notice that in the rear panel the lights did flicker when he moved the connections on R1 and R7. going to check for fluctuations. Engine continued to run even when we unplugged the R1 panel and all the light shut off.
3. This is an option, provide a second switched and fused hot wire to the ECM direct to the battery as we believe the ECM is having the power drop and it thinks the ignition is shut off.
4. We are going to shut everything down. Isolate it and let the ECM sit with no power for a week and then try a start.
5. This is an unknown at this point but the ECM may be failing. Although usually the ECM just fails and just goes dead. The mechanic / TECH has not seen this with a C13 before but, other CATS and some Dodge cummings have done similar actions.
6. Check the grounds on the transmission.
I think I answered all your responses. Thanks, as this ghost is keeping us from using the coach and doing events as it is unreliable at this point.
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Sorry missed this one.
Alternator checks out, putting 14+ volts and amps are good.
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Jim
On many of the Beaver coaches with vcat engines there is an ECM power supply relay , on the older coaches it was located in the back left corner of the battery bay not sure where it would be on yours ( that may be your problem)
Looking at the sciatica on page 105 of the 2007 Patriot wiring diagrams on coach assist the ignition relay is on board number 1 in the rear run box
The front /rear ignition control selector switch is also shown .
I have replace a couple of those front rear selector switch that failed ( they are usually exposed in a rear service bay with back open to the weather and road debris that and the fact they are rarely used leads to dirty connections inside and failure )
You may have either a failing front/rear ignition control switch or failing ECM relay.
Eric
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Jim,
Circuit board #1 in the rear run box, the PCB that Eric is referring to, is a known failure point for the 2006 and newer Patriots and Marquis. When PCB1 is failing a “Eng Comm Failure" notification will be initiated, and the engine will shut down.
The remote start and front/rear selector switches are mounted on this board.
Search for this, “2008 Navigator; Intellitec 73-00825 rear run box board bad. Workaround?” and you’ll find some troubleshooting and workaround suggestions. Also, suggestions for repair of PCB1.
Circuit board # 6, rear run box. When the ISO LED is illuminated it is indicating that the Big Boy relay is energized. Even when no charging is taking place, the Big Boy will remain energized until the surface charge of both battery banks has dissipated, both battery banks must drop below 12.8-volts. This can take several minutes depending on the 12-volt load.
Look at “Coach Assist->Common Problems->Battery Charging Systems” for a good explanation of the operation of PCB#6.
-Scott
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AWSOME information Eric and Scott!
Scott The owner and I trouble shot it together yesterday and we came up with a switch power to the ECM as an additional connection so if it dropped from the boards the ECM would stay hot and not drop out. Your post helped me walk through the issues and they almost perfectly matched and he was going to check that board out and get back to me.
I am going out of town, so they are going to shut everything off and let it cool down and drain power from the boards and then see if they can get the problem to duplicate so they can positively identify the failure. Also, the generator may have just help with additional power but, we were also pushing on that switch trying to get it to run and it may have just made the connection.
I will update you all late next week.
I will be happy to buy you both a cold one for this!!!