Ford Powerstroke Diesel Forum banner

CHECK CHARGING SYSTEM while towing

9K views 9 replies 6 participants last post by  Bryan72D 
#1 ·
First post. Didn't want it to be in this section. I've had a great time lurking, but I'm stumped with my problem. Here's the timeline:

Background: Bought a 2008 Job 1 F250 4x4, XLT, SRW, CC about 4 months ago. Put a fifth wheel hitch in, bought a fifth wheel and towed the FW about 6 times over hilly terrain to local campgrounds with no problems.

Today: A friend of mine bought a FW but needed me to tow it home for him today. I hooked up as usual. No indication that anything was wrong electrically. Got all normal indications as far as passing the turn signal/brakes/flasher check. Had the trailer brake gain indication as expected as soon as I plugged in the trailer plug.

Took off down the road. While getting on the highway, the battery light illuminated on the dash. I continued to drive the truck to the next exit. While driving, all gauges on the dash and the trailer brake gain indication cutout. Gage needles fell, gain indication went out. Then they came back with the battery light still illuminated. Then they went out and came back. This happened approximately 4 times.

We made it to the next exit, pulled into a parking lot and I unplugged the trailer from the truck, went back to the truck. Battery light remained illuminated. I pushed on the accelerator and the battery light cleared. My friend and I then started to check out the camper. I asked him to check the battery level on his battery indicator inside the camper. Dead. Didn't even light up the "E". Went to the battery compartment and saw that the previous owner still had the battery disconnected and the leads were in contact with the chassis. At this point, I accounted the battery light and loss of gages to the battery leads in contact with the trailer chassis. We taped off the positive lead, plugged the camper back into the truck and continued down the road.

Shortly after getting back on the highway, battery light comes back on. Now I'm concerned that my truck batteries are going to die and I won't have any source of trailer brakes. I pushed the HOLD TO PERFORM SYSTEM CHECK and it comes up with CHECK CHARGING SYSTEM so we pull off again. I start to check fuses in both the passenger compartment and the power distribution block. No smoking guns. I call the nearest Ford Dealership and they agree to squeeze me in. I tell my buddy that I'm concerned about the trailer brakes and that I needed to get the truck checked out before we continued on (still had about 30 miles to home). He agrees and he and his family stay with the camper in a BJ's parking lot while I run 6 miles down the road to the dealership.

After the camper is unhitched, I'm off to the dealership. No battery light though. I push the button, CHARGING SYSTEM OK. Now I'm baffled. I continue to the dealership and explain the situation. They offer to run a Charging Systems Diagnostic. Diagnostic comes back clean. No charge (no pun intended). Thanks Ford. I'm on my way back to the camper. On the way, I ask my buddy to reconnect his battery and see if it is indeed dead. It was. He buys a new battery and installs it in the parking lot before I get back.

Back on the road, battery light comes back on. ARRRRGGGGHH! I decided to continue. This time though, gauges never died, Trailer Brake gain stayed lit. A few more miles down the road, battery light goes out. Now I'm puzzled, but feel pretty confident that we're still safe. Over the next 25 miles, the battery light cycles on and off approx 5 more times. I determine that when the engine is worked hard (i.e. pulling up a steep incline, above 2500rpm), the battery light will come on within a few seconds of going over 2500rpm.

We make it back to my buddy's place safe and sound, unhitch and I'm headed home, obsessing about the battery light. I decided to pull my camper around the block and see if my camper will recreate the problem. Sure enough, pulling up a hill close to my house, the battery light comes on. I've never had this happen prior to today.

My observations:
1-Only happens when I'm towing the FW.
2-Battery light comes on only when the engine rpm exceeds approx 2500rpm.
3-Fuse 33 TRAILER TOW BRAKE CONTROLLER, TRAILER TOW BATTERY CHARGE RELAY COIL not blown (located in Passenger Compartment)
4-Fuse 44 TRAILER BATTERY CHARGE RELAY not blown (located in Power Distribution Block)
5-Relay 56 TRAILER TOW BATTERY CHARGE operating correctly (checked for continuity with jumpers and a 12V power source).

My theory: The cause of the problem was the loose battery leads coming in contact with the chassis of the camper. My truck was essentially trying to charge the chassis and the campers motion was causing the leads to move and sporadically short, which in turn caused my gauges to die, come back to life, die, etc. This also smoked a component in my trailer charging circuit. The dealerships diagnostic passed because the trailer charging circuit no longer had anything plugged into it, therefore was never truly tested. When the camper was plugged back in, problem returned. That's why I have the problem with both my buddy's FW and my own.

Where to go from here: I've checked the low hanging fruit (fuses, relays). Fuse 33 seems to indicate that there is a charging coil. I don't know where this is or how to test it. My 30-second Google search provided nothing.

I could coordinate with the dealership for a diagnostic with the camper attached but I would have to recreate the problem right before I pulled the truck in. The battery light goes out approx 10-15 minutes once the engine rpms settle out. I'm not sure of the size of the diagnostic machine but I'm assuming that the dealership wouldn't be too keen on me having the camper attached. Additionally, since I have a FW, I had an in-line trailer harness put in the bed of my truck, so there's a chance that a technician would tell me that it's probably the harness and start with that, when in fact, I'm very confident that it isn't.

I'd appreciate any troubleshooting ideas you might have. I've taken the truck with no camper attached on the same roads and worked the engine in the same manner to try and recreate the problem without the camper attached, but it never happens, thankfully. This is why I'm sure that it's limited to the trailer charging ckt in some way.

Again, thanks in advance.

-Neil
 
See less See more
#2 ·
I'm assuming you've tried to recreate the problem without the trailer, by running the engine over 2500rpm? I'm wondering if the direct short in the trailer while the truck was attempting to charge the trailer battery might have damaged the alternator or some other part of the charging system?

Beyond that, it almost has to be something with the truck wiring, since you have recreated the problem with two trailers now. I would disconnect the pigtail going to the in-bed wiring and run the trailer connected to the 7 pin at the bumper. This would tell you if it is the pig-tail spliced harness or something else in the truck.

I've had a dead battery in my 5th wheel before and the truck was able to power/charge the trailer w/out issue. My guess is the direct short screwed something up though.
 
#3 ·
Yes, tried to recreate with no trailer and haven't been able to do it.

I would think that the diagnostic that the Ford Dealership performed would've identified anything wrong with the alternator. Unless there's some magic that happens above 2500rpm with the alternator output that their machine can't diagnose.

The reason that I don't think it's in the harness is because the fault comes and goes. If there was a short or an open, the problem would exist all of the time, or appear randomly as I drove over bumps. I wouldn't expect it to be able to be recreated under certain rpm conditions if this were the case.

I don't want to sound like I'm biting the hand that feeds me. Just thinking out loud. Thanks.
 
#6 ·
I would think that the diagnostic that the Ford Dealership performed would've identified anything wrong with the alternator. Unless there's some magic that happens above 2500rpm with the alternator output that their machine can't diagnose.
You are probably right about Ford's diagnostic test, but there could still very well be a problem that could originate from your alternator... the internal voltage regulator may not function properly at a given RPM with a load. When the wiring touched the chassis, it may have shorted an integral component of the voltage regulator. Do you have single or dual alternators? I would also disconnect both your truck batteries and check them with a multimeter and a load tester. If needed, charge them and then re-check with a load tester to determine if they are accepting a charge (you may have an issue with one of your batteries). You could attach an amp clamp(if you have access) to the alternator lead which could give an idea what kind of output your alternator is producing. I hope this helps.
 
#4 ·
Additional question: Is there an OBDII reader that could tell me more than my on board diagnostic as far as when the battery light comes on? Something that I could buy and plug in, hook up my camper and then recreate the problem?
 
#5 ·
Explain to the dealer it only happens with the trailer on and make an appointment to go with the trailer on. I was having problems with a 6.0 that only occurred while towing. The dealer sent the tech out with me and the trailer on and narrowed it down.
 
#7 ·
Made an appointment with the Ford Dealer on jt720's recommendation. When I explained it to them, I asked if they had a portable diagnostics tool that we could take with us and he said yes, they did. Hopefully we'll get to the bottom of this.
 
#9 ·
Just wanted to close this thread out. During the 3 days between making the appointment and actually taking the truck in, it began to show the battery light without the camper attached. When I arrived at the Ford Dealership, The tech had spent some time reading over my post that I had printed out to describe my problem. Then they ran a charging diagnostic and all looked well to them with what my alternator was outputting. I asked if we could hook up the diagnostic computer to the truck and go for a ride.
Once he hooked up the computer, he did see some codes that didn't necessarily cause a check engine light. We took off with the camper and as soon as the battery light came on, he saw it on his laptop. We then returned the camper to the dealership and went for another ride just to confirm that it wasn't the camper. Did the same thing. He said that it was most likely the voltage regulator on the alternator, but had to make some phone calls to make sure.
He wrote it up in such a way that my Ford ESP warranty covered it. I've had nothing but good experiences with my Ford Dealership so far. Alternator was replaced and no more problems. In fact, we just returned from a 1400 mile round trip and averaged 16.4 mpg in a Job 1 with a Job 2 air dam. No issues. I love my truck.

Thanks guys for all your input/suggestions.
 
#10 ·
I had the check charging system message flash every time I started the truck. Didn't think anything of it, figured it was running a diagnostic. Then one day I had the radio on for all of about three hours and my truck wouldn't start. Jumped it, grumbled, then took it to dealer because my traction control light was going crazy in 4x4 and nuts in 4x4 low. Turns out the check charging system was a separate issue related to the passenger side battery and (here's the weird part) my passenger side hub having an air leak. Apparently there is a TB related to this and they replaced the battery and the hub on warranty. They managed to slow down the craziness with the traction control lights, but it'll need to be looked at again.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top