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Old 10-28-2013, 11:55 PM   #1
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Cat cranks but won't start

Coach - 1999 Beaver Monterey 30’, 300 CAT

PROBLEM: coach cranks but does not start; there is no white smoke when cranking, and no diesel smell at the tailpipe, so no fuel flow. Generator runs, so I'm not out of fuel.

Recent work done since the last time the coach ran and prior to experiencing this problem:

removed one house battery (dead cell, boiled over)
replaced AC blower motor
Worked on rattles under dash and in wiring behind driver’s side kick panel (tied harnesses up with zip ties to prevent contact with steering column). This is where I think the problem is - I think I goobered something up under there.

Troubleshooting done so far (after reading every post here I could find on this subject):

DATA:
No check engine light at power on
No pre-heat light at power on
No codes are set in the Silverleaf (not stored there, but read from ECU)
All engine history and MPG data is missing in the Silverleaf (not stored there, but read from ECU)
Silverleaf shows no temps
Silverleaf shows no change in cruise control state when switched (comes from ECU)
Silverleaf shows communications with transmission (Data icon active, "no lockup" indicator on, switching from neutral to drive when engine not running triggers a warning)

POWER DISTRIBUTION:
All fuses on the “Beaver Box” (ECU and Data Logger fuses, Intake heater fuse and relay, solar fuses) are OK (pulled and checked)
In front electrical bay, power is present on the output side of the power distribution bus at power on for all ECU connections
Bosch relay in “Beaver Box” was removed and re-seated. Chatters when fuses are pulled and when re-seated, relay replaced with no effect.
Power is available to the Intake air heater relay, but does not get switched @ power on

POWER @ ECU
Chassis harness connector was disconnected from the ECU
Unswitched power is present (pins 52 and 53)
Could not verify battery negatives (pins 65 and 67) as hard grounds, appears to be a slight resistance there (~10 ohm), but no other reference as to where these wires go
Ign key switch signal does not appear at power on (pin 70)

THINGS I HAVEN’T DONE YET:
bridged Intake Air Heater relay and then tried to start (don’t think there’s any fuel present)
Looked for ECU signal at Intake Air Heater relay connector (don’t think the ECU is up)


This leads me to believe I damaged the key switch wire when working under the dash, but a visual inspection reveals nothing. I didn't bash around under there, so it's probably something subtle.

Unfortunately I don’t have a wiring diagram for this coach, and I’ve called Beaver Coach Sales before and nobody has been able to find one. I have a 1995 Patriot diagram and a few other pieces of Beaver diagrams people have sent me that gives me a general idea of how Beaver did things. However, I really need specific details on how that keyswitch signal gets to the ECU. pinouts of each connector along the way, etc.

Any other ideas?
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Old 10-29-2013, 03:39 AM   #2
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sounds like your problem may be in the wiring under dash to ignition switch ie, no switched power to ecm, no wait to start and no check engine light. I would check ignition switch for power outs and check relays. My coach as many others use an ignition switch from and older chev pu (1971) and the switch controls relays to provide power to ecm and fuel solinoids.
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Old 10-29-2013, 09:05 AM   #3
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what's really strange here is that everything else that is controlled by the keyswitch works,so I'm trying to figure out where they split it off to run the length of the coach since the stuff controlled up front is OK.
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Old 10-29-2013, 09:17 AM   #4
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What kind of fuses are they-blade/tube type? How did you test them-looking for broken fuse or ohm meter? I have had fuses that look good but aren't. 10 ohms at 1 amp would be a 10 volt drop on the ground side
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Old 10-29-2013, 10:56 PM   #5
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Sounds like no power or a loss of ground at your engine ECM.And the ECM cannot communicate with the other ecus without power. If you can give me a engine serial number I can tell you which wires/ pin numbers at the engine ECM should have power and ground. If that would help.
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Old 10-30-2013, 12:19 AM   #6
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Quote:
Originally Posted by VanDiemen23 View Post
what's really strange here is that everything else that is controlled by the keyswitch works,so I'm trying to figure out where they split it off to run the length of the coach since the stuff controlled up front is OK.
The ignition switch will have at least two outputs with key on, one that stays hot while cranking (computer feed, guage feed ect) and one that's hot only when key is in run (wipers, ac heat ect). You could have lost the first one or as stated, a ground can cause this. A relay also.
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Old 10-30-2013, 01:31 AM   #7
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Cat - you hit the nail on the head. I knew I was over thinking this. Back in the battery compartment there was a thin ground wire disconnected when I took out the bad battery. It was marked as the ground for the solar system, but when I went out to connect it at 9:30 PM I got sparks - and the coach fired right up at next attempt.

Now I have a funny thing going with the inverter - that might have been the start of everything with the boiling battery.
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Old 10-30-2013, 10:49 AM   #8
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spoke too soon, went out this morning to work on clearing the inverter problem, and the start problem is back. both battery banks are showing over 12V, but the ECU relay was chattering away. I either have two separate problems that are confusing each other or two problems working together.
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Old 10-30-2013, 08:36 PM   #9
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Still sounds like a ground,power issue, should have a better ground than one thin wire. The small wire may have grounded it for a bit. Most of the wires to the ECM should be 16- 18ga wire which isn't huge put not real thin either.Many of the Cat engine ECMs have more than one power and more than one ground.

Offer still stands if you can give me the engine serial number I'll look up the wiring schematic for your Cat engine ECM.
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Old 10-31-2013, 01:30 AM   #10
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So here's the whole story....

Overnight researched the inverter problem and it seems to clear all the crazy behavior I needed to disconnect it from all power. So I unbolted the dc leads for a few minutes, hooked it back up, and not only did the crazy behavior continue, the no-start problem returned. I called xantrex and they said the inverter had to be disconnected for at least an hour, and they suggested load testing the batteries.

Went home at lunch, pulled all the batteries and took them to NAPA for testing. One of my new chassis batteries was bad, as well as the house battery that boiled, and two of the remaining three house batteries were marginal.

When I came home with the new stuff, I took an hour to straighten out the rats nest of cables in and behind the battery tray. Beaver is pretty good about using silver marker foil to identify their signals. There were three wires marked "coach Solar", "house Solar", and "Solar Ground". I assumed that the 4th wire was the other solar ground - but it was a dedicated ground for the ECU - I had to pull about 10 inches of wire out of the protective sleeve to find a legible marking.. So when I removed the boiled battery and disconnected that ground, I induced the starting problem. The reason I thought I had no keyswitch was because I was measuring from the keyswitch pin on the Chassis ECU connector and the corresponding ground pin - except there was no ground!

The fact that the motor cranked over just fine and all the other items on the coach worked until the inverter went into crazy mode led me to believe the batteries were OK.

There were some other signs of battery problems, like the ECU relay chattering, but I was really more concerned about the Xantrex showing 14.5 volts when neither battery bank was above 12.5.

All in all, a lot of confusing data. Next time I have to keep it simple.

I put my engine book back in the MH - packed it for a race this weekend - but I'll PM you with the numbers because I'd like a reference I can really trust.
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Old 10-31-2013, 01:40 AM   #11
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Also... check for AC bleeding over into the DC side of things. Set your volt/ohm meter to AC scale and check across a few different 12vdc sources. Some converter chargers while in the process of failing will bleed a lot of AC over the DC lines. While I've never had one bad enough to bring down an ECU I have seen a failing converter mess with just about everything else inside of a coach, AC units, refrigerators, tank level monitors, LP/CO detectors, laptops, etc etc.
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