Engine quits on highway and restarts in 5 seconds

[John Hennessey]

We have a 2003 Marquis wth a C12   We’ve replaced the ignition switch and the starter solenoid and once and a while we are going down the interstate and the engine quits the speedometer goes to zero and in 5 seconds it restarts itself. Any ideas?

[Joel Ashley]

First inclination is an insecure "run" wire at the new ignition, a loose main chassis or ignition circuit ground wire, or a faulty replacement ignition.  Check also the integrity of the ignition circuit breaker connections and the main 12v system solenoid, low in the electric bay, streetside front bay. 

In fact, that solenoid's history on this Forum makes it a very likely culprit in your case, and a candidate for you to replace or upgrade to an electronic version.

Joel

[Doug Allman]

John, Joel could be correct but one other excellent source is Dave Atherton whom is a 42 year retired CAT Technician. You could use the ASK DAVE section in the TECHNICAL heading.

[Dave Atherton]

Gentleman, there are many ways failure happens with our Caterpillar electronic engines. Approaching
subject from different directions from past member problems. Not being in driver seat, it sounds like
what is called an event happen that starts up and runs again. Sometimes event code will
appear than sometimes it will not. It appears or acts like there is a sensor called Atmosphere
Pressure Sensor is causing the problem. Caterpillar part number 161-1703, if event code is
present should read 108-4. Dave Atherton Retired Cat Mechanic

[Gerald Farris]

John,
Ignition switch failures on your model coach are very rare because it carries very little current. Most of the current that is controlled by the ignition switch (40 to 60 amps) is actually controlled by the ignition solenoid in the LF electrical bay. The ignition switch controls this solenoid with just a couple of amps making the failure point at the solenoid. These solenoids fail so often in the 10 year range that I carry a spare solenoid in my coach. This solenoid is rated at 85 amp continuous duty, and it should never be replaced with a lower amperage rated solenoid or one that is not rated for continuous duty. It has been discussed on this forum many times.

Gerald

[Joel Ashley]

I totally agree the solenoid is pretty suspect, the most likely culprit in John's case, and easy to replace (as long as the diode is mounted correctly in the process). 

But my comment re. the ignition is based on experience.  Though the GM ignition should be reliable and as a consequence is arguably the most common one used in motorhomes of all makes, the one on our old Pace Arrow failed, was replaced by one from a junkyard Chevy van, and that one as well (that time with a new one) a few years later.  Don't ask me where the high current came from, but heat was the problem.  Then we had issues with the Beaver's ignition in 2012 while parked in Nebraska proximal to Missouri River humidity and 110F temps for a month. 

So it does come to mind first when others report they've replaced their switch.

Joel

[john brunson]

Somewhere, I recall ppl replacing the stock solenoid with a much much morobust solenoid... can someone remind me?  My 200 amp replacment solenoid form the golf cart shop solenoid is running quite warm... it's only a matter of time

[Joel Ashley]

Try this thread:
http://beaveramb.org/forum/index.php/topic,3423.msg26078.html#msg26078

Joel

[Paul Bowers]

Had this problem a couple of years ago with my CAT.  After trying to fix the problem myself, I carried to the local CAT dealer.  Hooked their Computer to the coach and found several fuel controller faults that were in the history.  A couple of different engine program "tunes" had been issued since the coach's last update.  He erased all the past faults, reinstalled a new computer update and he coach ran great again.