Throwing P0500 code and continiously blowing IGN1 No. 2 fuse

That scorching is the results of a loose pin to pin connection. Acts like a heater, high resistance. You need to either clean that up and tighten the female or replace the connector.

 

Could it be getting hot enough it blows the fuse to prevent a fire?

 

Yup. What is the wire controlling? (i.e. parking lights, Brake signal)?

 

If I am reading the diagrams right it is high fan speed on the blower motor.

 

Well, I'll change my answer to "Maybe" .
The connection between heat and amperage is related, but how do we know what amperage was causing this discoloration. As Stated above, a resistive connection acts like a resistor witch generates heat and this circuit (10A?) and 12V gives Amp x volts = Watts = 120W Max Possible until the fuse blows. Since your fuses sometimes vaporize that's a dead short to ground and may not related to this connection issues.
But never the less it needs to be properly cleaned / repaired/replaced. From what I understand the connectors AND wiring should exceed the rating of the fuse by the factory.

I have seen this on one of my AC fan switches in past vehicles (78 Ford Squire /Wagon?) - the plastic at the switch just melted but did not blow the fuse.

To ensure that the fan wire is not the issue you could disconnect the wire (i.e. cut) coming right out of the fan and run a new wire to a "switched" power source from the fuse box and fuse it just over the Max amps of the fan. Leaving the rest of the circuit as originally wired. Then the NEW fuse will blow if that's the issue. You can always rewire it back later after this is fixed.....

 

I seriously doubt that it caused the fuse to blow. High resistance = reduced current but causes heat. That is why it is discolored.

 

Unfortunately for Daniel, I can guarantee that this connector is not the cause of IG1#2 fuse blowing, as the HVAC fan and switch does not get its power supply directly from IG1#2 fuse.

That's not to say it doesn't need to be fixed, personally, I'd replace the female connector pins in the harness connector body, clean the male pins of the switch with some fine emery, then apply a light film of dielectric grease before assembling.

Then continue to hunt down that nasty shorted or grounded circuit and beat it like a red-headed step-child.

 

08TRDOFFROAD, have you found a solution? I have a 07 TRD and am experiencing the exact same symptoms and same fuse is blowing, but i don't tow anything. I do have the tow package and the adapter for trailer but haven't checked that yet. The code reader I used gave a 0500 and also indicated " vehicle speed sensor a ". I will be installing that part tomorrow when the sun comes up. Can anyone tell me where the Vehicle speed sensor is located? i already checked the wheel speed sensors but not sure where the Vehicle* one is. I think its on the rear differential and I noticed Im leaking oil right on the sensor if thats what it is.

 

manual 6 speed -- vehicle speed sensor is located on the transmission.

 

also clean the sensor head , clean it very well with electronic parts cleaner. remove any dirt, or grim.
Look for any chaffing on the wires & repair. I would ohm the sensor as well, with the new on so you can compare it. If it ohms same as the new one after being cleaned i would stick some dielectric grease in the connector and give it another go.

hope this helps.

-Kev

 

I have a Automatic trans, will the sensor be in the same place? I just picked up a brand new vehicle speed sensor and alternator and will be installing them in the AM. That speed sensor was $120 and is a tiny little thing...

 

yes driver side towards the middle of the transmission.

 

Thank you! The sensor was very easy to replace. It was on the bell housing on passenger side like you said. I replaced the sensor, and the alternator and blown fuses and problem solved !! all codes are now off, truck runs fine, speedometer is back and battery is charging fine. Im sure it was just that sensor but I replaced the alternator anyways because I have 132k and would rather have the peace of mind for future trips.

 

AWESOME!

thanks for checking back. Was the old sensor damaged? Did you ohm it out ?

Glad it worked out for you

 

Don't ohm it out! If I spent 120 for a new part, I have to assume the old was bad, to keep my sanity. Just keep it in a toolbox ahem, just in case.

 

I just replaced the sensor. Idid notice on the small metal tip, half of it had some metallic dust stuck to it and some minor purple color, but when i wiped it off with a terry cloth it looks new again. For my own sanity I just replaced the sucker for $90. btw.. what does " ohm" mean?

 

Checking the resistance of the coil in the sensor with an ohm meter, or multimeter.

 

Plot thickens. Haven't towed the trailer in abouta year. Blew the fuse today again with nothing in tow. Problem is isolated to the truck...somewhere.

 

I believe engine rpm had something to do with it. I am going to replace the blower motor resistor and see. May end up having the ac compressor replaced as the magnetic clutch could potentially be the culprit if the.resistor does not resolve the problem.

 

Replaced the blower motor resistor and charred plug tonight! Tightened up the connections while I was at it. Hopefully this will be the last of this issue. Next step will be replacing the magnetic clutch on the comressor if the condition occurs again.