Diagnosing bad ingnition switch

[ecgreen]

OK, just installed a rebuilt 2.9l. Battery is good, brand new cables and new starter relay. Turn the key to start and I get lights fuel pump and no click. When I unplug the red and white ignition wire on the relay and run a piece of wire from the positive battery terminal to the s-terminal on the relay I can get it to turn over. So I figure its that wire or the ignition switch. I accessed the switch and put a test light on it. Yellow wire is always 12, which it should be. When I turn the key to on I get voltage at both the brown and pink wire and the red and light green wire. Shouldn't only one of these wires have voltage? Is this supposed to happen or is there a short?. When I put it on start, I get voltage on both of those wires as well as the pink wire. Seems to me this shouldn't be - but I am a total noob. Below is the diagram. Awaiting u[pload of 2.9 brilliance...

 

[Curious Hound]

OK, just installed a rebuilt 2.9l. Battery is good, brand new cables and new starter relay. Turn the key to start and I get lights fuel pump and no click. When I unplug the red and white ignition wire on the relay and run a piece of wire from the positive battery terminal to the s-terminal on the relay I can get it to turn over. So I figure its that wire or the ignition switch. I accessed the switch and put a test light on it. Yellow wire is always 12, which it should be. When I turn the key to on I get voltage at both the brown and pink wire and the red and light green wire. Shouldn't only one of these wires have voltage? Is this supposed to happen or is there a short?. When I put it on start, I get voltage on both of those wires as well as the pink wire. Seems to me this shouldn't be - but I am a total noob. Below is the diagram. Awaiting u[pload of 2.9 brilliance...

According to the diagram you posted, your observations are correct and normal. The brown/pink wire and the red/lt green wire are connected to each other at junction s207.

 

[ecgreen]

Got it. And if no one has said so today, thank you for your service

 

[Curious Hound]

OK, thats what that means on the diagram lol But should the br/pk be on when I have the key in the first position? Doesnt the diagram say that that wire should only have 12 volts when I attempt to start the truck?

Thanks for the help, you guys are so patient with us newbie idiots

The brown/pink wire and red/lt green wires supply items that need power in both the run AND start positions. The pink wire supplies items that only need power in the start position, ie; the starter relay coil. If the truck has manual trans, there should be a clutch interlock switch that the pink wire goes through as a safety. On automatics, I believe it's the neutral safety switch.

 

[ecgreen]

Just as I posted that reply I realized what you meant lol. I deleted it in a vein attempt to save face bwhahaha

 

[ecgreen]

The brown/pink wire and red/lt green wires supply items that need power in both the run AND start positions. The pink wire supplies items that only need power in the start position, ie; the starter relay coil. If the truck has manual trans, there should be a clutch interlock switch that the pink wire goes through as a safety. On automatics, I believe it's the neutral safety switch.

So I should be looking at testing the clutch switch next I am guessing?

 

[Curious Hound]

Yes. Thats where I would check next.

 

[ecgreen]

Just checked the clutch safety switch and I found my gremlin! I had 12 volts coming in on the 1st pink wire with the key turned to start. I depressed the pedal and 0 volts came out the second pink wire - no bueno. I noticed the switch wasn't seated right, so the spring wasn't engaging when I pressed in the clutch. I fixed that and BAM, she turned over. It didnt run, but I knew that from before - I'll solve that issue next. This is my first real successful electrical diagnostic, awesome stuff. Thanks so much for the help.

 

[Curious Hound]

Congratulations!