RV Tech Savvy: Engine Stalls When Brakes Applied

I have a problem with my Itasca 2005 Horizon 36RD diesel pusher on a Freightliner chassis with a 350 Cat engine. The ABS light stays on when the engine is running, and when I apply the brake pedal, the engine quits. It happened two weeks after the motorhome was parked at a campsite. I cannot drive the motorhome because if I put my foot on the brake, the engine stalls, so I cannot put it in gear. Can you help?

Andre Lacombe | Montreal, Quebec, Canada

Freightliner confirmed that there is no direct electrical connection between the brakes and anything that would cause the engine to quit. My first suspicion was that a rodent had chewed through the wiring, which is quite common when motorhomes sit idle even for a few days. This could cause some sort of cross path in the wiring once the insulation is chewed away in a harness. After a follow-up conversation with Lacombe, it was determined that faulty ground connections at the battery were causing cross feeds in the electrical system, and correcting them solved the problem. The lesson here is to always check and clean all of the battery connections, and when chasing weird symptoms, look for faulty ground connections.


Cranky Cranking

I have a 2001 Jayco Class C on a Ford E-450 chassis. Last summer, upon trying to leave my campsite, it wouldn’t start. After running the battery down, and [the Jayco] failing to start, I remembered I could start it off the generator battery. It started right up and ran as usual. Getting ready to store the coach for the winter, I encountered the same problem. It doesn’t seem to be getting gas, but as soon as I start the generator, the engine starts right up and runs well from then on. Is the fuel pump going bad? It runs fine after it starts, and Ford technicians can’t find any problems. I’m afraid I’m going to be stranded.

James Kissell | Newark, Ohio

Intermittent problems like this can be a nightmare. You’ll have to devise a test strategy to catch the faulty component “in the act,” so to speak. When a gas engine cranks over normally, but shows no sign of starting, the problem is either no spark or no fuel. Fuel pumps more frequently quit intermittently like this, so I would look at the fuel system before the ignition. Running the genset increases the available voltage and might bring the pump (or other failing electrical component) back to life temporarily. The fact that it is 17 years old adds to the likelihood of a failing pump (or relay). Start with a fuel-pump pressure test and leave the gauge on the engine, with the doghouse off, for a long test drive. Test it when hot and under a full load on a long hill. Sometimes you can get a recalcitrant pump working again temporarily by banging on the bottom of the tank.


Dinghy Disconnect

 

 

We purchased a 2017 Chevy Colorado 4×4 to tow behind our motorhome. The owner’s manual says the last thing to do when hooking up is to disconnect the battery in the Colorado. No one has been able to tell me why I am disconnecting the battery.

Michael Charter | Jericho, Vermont

This is to prevent the battery from becoming discharged during towing. To make it less inconvenient, you can install a battery disconnect switch so that you won’t need any tools when hooking up or unhitching the dinghy vehicle. These are readily available in many RV shops and auto parts stores.


‘Chirping’ Sound

About two years ago I purchased a 2004 Winnebago Minnie 31C Class C motorhome with a Ford V-10 engine. The motorhome was in good shape, with only 14,000 miles on the odometer. I put new tires on and changed the fluids before taking our first trip in the motorhome. There is a noticeable chirping sound that seems to be coming from the engine compartment. As the travel speed increases the chirping sound also becomes faster, until being inaudible at 45 mph and above. I replaced the serpentine belt, thinking that might be where the chirping sound was coming from, but it made no difference. We have traveled about 3,000 miles since then and the engine seems to run fine, so my only concern is that the chirping sound may be an indication of future problems. Where do you think this sound is coming from, and will it likely lead to a breakdown as we travel this year?

Alan Brown | Nevada, Iowa

About the only thing more difficult than finding a chirping sound that occurs while driving is finding it remotely by email when you can’t hear it or test drive the motorhome. Besides belt noise, I’ve even heard sounds like this from the wind going through grilles, etc. Also, sometimes a front brake will make a sort of chirping sound. Often, wind, engine and tire noise will drown out these sounds at highway speeds, which may explain why you don’t hear it.

Have a tech question?You need to devise a strategy to determine where it’s coming from before you can fix it. Find a traffic-free straight-and-level road that you can drive on. When the noise occurs, try putting the transmission in neutral and see what happens. While in neutral, try revving the engine and note if that changes it. Does it vary with vehicle speed or engine speed? Try applying the brakes and listen for a change in sound. Have an observer stand at the side of the road and listen for the location of the sound as you drive past. If necessary, try switching the engine off (only do this where it’s safe and at lower speeds; power steering assist and the brake booster may not work). If the noise goes away with the engine off, it indicates the engine is the source. Remove the engine doghouse and test drive with an assistant to listen for where it’s coming from. I think these techniques will lead to the source of the sound. The fact that the engine runs normally, and there’s no check-engine light, reinforces that this is not a serious condition.


Descending Steep Grades — Comment

This is in regard to the January question about “Descending Steep Grades.” I think the use of a tow/haul feature of the transmission should have been addressed in the response, but I hope Kenneth Barnes was able to read the response to the following question in that section about “Shifting Gears.” Barnes’ 2017 Thor Windsport with the V-10 surely has the tow/haul transmission, and he will find it helpful to learn to use it.
I had a 2015 Thor Vegas on the Ford E-350 chassis with the V-10 and a five-speed automatic transmission, and now I own a 2018 Forest River on the Ford E-450 chassis, which has a six-speed automatic transmission. Both of these units have the tow/haul feature. I use the tow/haul in the mountains of Colorado and coming down off the Mogollon Rim in Arizona, towing a dinghy, and the tow/haul feature is a life- (and brake-), saver. I hardly have to use brakes at all on the down grades, and if the unit starts going a bit faster than I like, I lightly brake so that it doesn’t downshift to the next lower gear.

Gene Shannon | Colorado Springs, Colorado

Thanks for taking the time to write, Gene. When I wrote the reply, I guess you could say I assumed that when Barnes spoke of downshifting, he was also using the tow/haul feature. However, this may not be the case, so thank you for pointing that out. This is an important safety feature as well as a convenience that drivers should use.


 

1 COMMENT

  1. I’d check to make sure the torque converter lock up is not stuck. If it is, it would keep it in gear and the engine would be lugged to a stop. I have my van with a switch on it, due to other problems, and if I hit the brakes without turning off the torque converter lock up switch, it will choke down the motor…

LEAVE A REPLY

Please enter your comment!
Please enter your name here