Throwing P0500 code and continiously blowing IGN1 No. 2 fuse

Hey all,

I am experiencing something rather frustrating with my truck and the issue has already ruined a hunting trip my wife and I had planned for this week.

Here is the problem. The truck keeps blowing the IGN No. 2 fuse so I lose speedo and the abs and e brake lights come on, the cel throws the P0500 code which is a speed sensor malfunction. The thing that is really confusing me is it only does it with my trailer connected via the seven pin. I have been through the writing on both vehicles as thoroughly as I can and can't find a short that would cause the problem.

It had only done this once before now, i changed the fuse and all was well. I'm at a loss and don't dare take the truck on a 10 hr round trip with the problem. I already went through four fuses just trying to get back from the hour away I had already driven.

Please help!

 

Is the battery in your trailer charged, or dead from sitting? I don't have a diagram, but if its charging the trailer battery directly off the IGN #2 fuse then that could be your issue. In any case, it sounds like the issue is in your trailer somewhere.

 

The trailer battery is fully charged. I've had the trailer plugged in for the last three days in preparation. The battery is brand new too!

But, the plot thickens, while I was parking the trailer, it blew the fuse without the seven pin connected. Only thing that was trailer related that was connected to the truck is the brake controller, but that is powered by a different circuit. So I am pretty sure I can rule the trailer out as the cause.

 

I am inclined to side with landphil at this point. Especially if it never happens without the trailer.

 

Well I spoke too soon then. lol.

 

Could a failing speed sensor blow the fuse?

 

Not likely because it simply sends a signal. No chance of over-voltage on that one. I will have to look on Tuesday, if you haven't found the issue yet, when I get back to work and log into my diagnostics information.

 

Are you sure the brake controller is not on a branch circuit under IGN-2?
Those are your primary fuses under the hood near the battery, and they feed branch circuits that are individually fused both under the hood and under the dash.

There could be a problem with the brake controller.

I don't think the speed sensor could blow that fuse... it's all small wiring and the thing is little more than a simple pulse generator. The 500 code is being triggered because of the loss of the speedo signal, not likely the other way 'round.

 

Something on the trailer shorting to ground? Seems like both 7 pin & brake controller would have a ground connection between truck & trailer. I guess just hitching it to the truck creates a corundum path via the receiver to the frame.

Does the fuse seem to blow "at random" or after applying the brake, cruise control, etc?

 

Brake controller is installed in the truck and connects to the trailer through the 7-pin connector.

 

Hmmm, a thickened plot indeed! I just went looking for wiring diagrams with no success, seems all the online ones are removed. Anybody have a source I didn't find?

I agree it won't be a speed sensor causing the fuse to blow, rather, the sensor is an input to the combination meter, AKA speedo. The combination meter is losing power when the fuse blows, so it no longer sends a vehicle speed signal to the engine ECU, and thats where the P0500 comes in. So, a carefull study of what IGN 1 supplies is key here, then systematically check all those areas from there. Maybe even inside the 7 pin socket on the truck, I don't think the OEM connector is any better sealed on the back side than a typical socket, is it?

 

From a previous thread, here's what's in IG1s path:

09-29-2011 | 10:52 PM
caribe makaira
10A IG1 = handles all that follows....

ABS (w/ VSC), TRAC, VSC, Auto LSD, Downhill Assist Control and

Hill–Start Assist Control

ABS (w/o VSC)

Accessory Meter

Air Conditioning

Back–Up Light

Charging

Combination Meter

Cruise Control (1GR–FE)

Cruise Control (2TR–FE)

Electronically Controlled Transmission and A/T Indicator (1GR–FE)

Electronically Controlled Transmission and A/T Indicator (2TR–FE)

Engine Control (1GR–FE)

Engine Control (2TR–FE)

Headlight

Multi Mode 4WD and Rear Differential Lock

Power Outlet (115V)





Rear Differential Lock (2WD)

Seat Belt Warning

Shift Lock

SRS

Tire Pressure Warning System

Trailer Towing

Turn Signal and Hazard Warning Light

Looking at threads here & on other sites, people seem to suspect the trailer reverse lights...drawing too much current due to either a short or a high-wattage backup bulb in the trailer.

 

Different fuse though, IGN #2 was the one in question here.

 

Update: still blowing the fuse without the trailer and brake controller connected. Has to be something in the truck itself.

A diagram of what the fuse supplies sure would be nice, but even the links on ttora aren't any good anymore.

 

I think I found an archives copy of the 07 wiring manual, but my phone won't let me open zip files...

 

From the '08 owners manual:
IG1 NO.2 10 A: Anti−lock brake system, vehicle stability control system, stop lights, charging system, multiport fuel injection system/sequential multiport fuel injection system, air conditioning system, instrument panel light control, clutch start cancel switch, rear differential lock system, power outlets, tire pressure warning system.

Since stop lights are tied to this, I'm still thinking trailer connector if this just started after you hooked up to the trailer to start this trip. The socket could be shorting internally, try unplugging it a foot or so behind the 7 pin socket, you'll see the connector there. Maybe check the brake light switch too.

 

Visually the harness and plug look OK. No charing or scorching that I could see.

Since the fuse is tied into the charging system, could a failing battery cause something like this? My truck still has the original factory battery that is going on six years old, it wouldn't surprise me if it is on its last leg.

 

It shouldn't be related to the battery, but a short in the field circuit of the alternator is a possibility. That said, battery load tests range from free to cheap, so I'd be getting it tested regardless, before it leaves you in a pinch.

I agree with door-dings last post too, trailer sockets are just that inviting for trouble

 

I'll pull it apart and take a look in the morning.

OK, just brain storming and the battery crossed my mind. I'll definitely get it load tested though!

 

Email to me, I'll unzip and send the PDF files back to you or post as attachments here.
I'd like a copy too... thought I had them but I don't.

Or instead of email, PM me the link.