Throwing P0500 code and continiously blowing IGN1 No. 2 fuse

It is ig1 no 2 that is popping.

I was not very close to home when I made my last post. I was closer to my destination so we rolled with one window down and the rear slider open with no ac and no speedo for about an hour to catch up to my inlaws who we were going to be camping with. On the way I racked my brain about what might have caused it. Prior to posting I disconnected the trailer and replaced the fuse. Still immediately popped eliminating the trailer as the culprit as what ever was causing the issue was still in a dead short state. Then began unplugging the radio, illuminated 4wd PCB, etc trying to find the cause but nothing resolved the issue. While examing the plug on the back of the ac control while sweating to death on the side of the road, I noticed a connection with a bit of scorching on it. Once at the gas station with my in laws it dawned on me that maybe my junk ticking blower motor had finally worn out and was shorting out after running long periods of time and now was at a dead short... Such as road trips towing the trailer. I unplugged the motor and replaced the fuse and the fuse did not immediately pop. So we continued on without the issue returning, although without ac. I still have a bit of testing to do, but I am cautiously optimist the blower motor is the culprit beings as the issue was a dead short and once the motor was unplugged I did not blow another fuse for the remainder of the trip.

 

My testing tonight did not yield the results I was hoping for. I plugged the blower motor back in and turned the truck on (hoping for an immediately blown fuse to diagnose this issue once and for all) not the case...everything ran normally. No blown fuse all the way to the rv dump and back. Is there a way to test the draw of the blower motor to see if it is drawing more juice than it should. I hate electrical gremlins...they are so hard to chase down. Especially on a circuit like this that spiders into everything!

Please do post link if you find the thread about the ac control board failure. I really like my truck...but if it can't reliably get my family around towing or not then I will be forced to get rid of it.

 

Honestly, I tried...I couldn't figure the dang thing out to get it off the truck...and was afraid of breaking it...any advice?

I am wondering if the wiring in my dash was damaged when my truck was burglarized and they ripped the stereo out...the problem showed up the next time I towed the trailer after it happened.

The thing that gets me is it is an intermittent issue and it happens with and without the trailer attached. If I could replicate it, it would be much easier to figure it out.

I am honestly a bit overwhelmed with it because it could potentially be so many different things.

 

Does anyone know if there is a sub harness in the dash I could just replace to rule out damaged wiring from the burglary? I have been searching an online parts catalog but can't find anything.

I really don't want to just throw parts at it until the problem goes away...but I don't know what else to do. I am going to pull the dash apart and look for any signs of a damaged wire as well as inspect the trailer harness for issues...beyond that, I don't know what else to do other than take it to the dealership...ugh!

 

Interested as well as to hoping you find out the cause of the problem

 

I'm not sure about the later style fuses, but the old glass AG fuses gave a clue to the problem. If it vaporized it was a dead short. If the wire just kinda melted and opened up it usually was an overdraw of amperage. I'm not sure if this still works on the plug style fuses, but I thought I'd toss my 2 cents in just in case. I'd definitely spend some time under the dash trying to see if there was any wires scraped, cut, resting on metal, etc,,, Best of luck and I'd like to hear your final outcome ...

 

The few I have looked at are pretty much vaporized with a small stub of metal remaining on the posts (I hope that makes sense). But the theory of melting vs exploding makes sense. I am going to pull the dash apart and inspect all the wiring. I am also going to inspect the trailer pigtail and possibly do the relocation mod while I am at. I wish it would just do it without the trailer being attached or recently attached to rule out the trailer all together.

I just don't understand why it only occurs when the trailer has been attached if it is a short in the dash somewhere. You'd think if it were a dead short in the dash it would do it off and on regardless of whether or not the trailer is or has been attached. Makes me wonder if it is something on the trailer. I have looked it over once, but I might take a second look.

 

If I am able to get the trailer connections apart, would you recommend putting a heavy coat of di electric grease on them?

 

Are you still getting the P0500 code?

 

Yes, I did again when the fuses were actively blowing and it stayed on for quite a while after before it cleared the cel on its own.

 

have you unplugged the vehicle speed sensor, then see if the fuse blows?

 

On MY truck (2012) the manual says fuse 9 for IG1 Back-up lights, air conditioning system, shift lock system, audio system . Since you believe this is related to the trailer, I'd check the wiring around the Tranny BU switch and if you see nothing remove the connector from the switch and wait to see if it still blows. I have another way to find this but you probably would not want to use it .... it's a little drastic but I've had it work for me out of sheer desperation ...

 

This is everything that is on the IG1 No. 2 fuse:

 

hard to diagnose from 3,000+ miles away but it sounds like the problem may be in the trailer harness. They easily corrode. Have you cleaned it out well with some electric parts cleaner and apply dielectric grease? Did you trace the trailer harness back and search for a frayed wire or cut in the harness? You can perform a wiggle test as well if a cut or frayed wire is not visible.

With the trailer plugged in, do all of the functions work appropriately?
ie: turn left blinker on - left blinker works on trailer
brake lights on - brake lights work on trailer
ect

Is the brake controller working properly? was it wired properly?

 

I would conclude that you are getting the p0500 due to the fuse blowing, you lose input from the cluster and it causes a p0500. It also clears itself.

I have seen the trailer plug wires deteriorate just behind the plug itself and cause a short. I have also see where the plug doesn't have a great connection with the connector and cause a short.

 

Absolutely.

If you're unable to disassemble the OEM trailer socket, I'd be replacing it and cutting the old one open to looks for signs of it grounding out - but that's me. When it comes to electrical issues, I don't like leaving possibilities behind - I like to be certain I've resolved the issue, though it can be hard when the issue is a intermittent like yours. So far the common theme here is pulling the trailer, but the fuse blew after the trailer was disconnected, which eliminates the trailer itself as the problem area. The 7 pin socket is the very next in line, more exposed to corrosion than any other electrical component on your truck , and disturbing it seems to wake the sleeping monster. For <$20 and an hour, you can install a new quality socket ( I like these http://www.hopkinstowingsolutions.c...v-blade/endurance_7_rv_blade_vehicle_end.html) and cut or break that OEM one open to know for sure whether you resolved the issue.

 

one more question.

Do you have the factory flat blade socket on the truck & is it untouched. Are you using any kind of an adapter from the trailer plug to the trucks socket?

 

One mechanical device in the list is the neutral start switch. I'd check the switch/connector and associated wiring for damage...

 

Sorry, for some reason I wasn't getting email notifications of new posts. I have the factory seven pin connector and it is untouched and undamaged. I do not use an adapter when towing this trailer, although I do use a seven to four pin adapter when towing my boat and haven't had an issue with the fuse blowing then.

 

Here are pics of the scorching in question!