Quote:
Originally Posted by ray_mcavoy
From reading through your posts, I'm going to say that you're most likely looking for a bad connection somewhere in the red wire that feeds battery power to the ignition switch or in the purple wire that runs from the switch down to the starter.
I know you have done some testing and have voltage present on these wires. However, a bad (high resistance) connection will still show voltage present on the wire when there is no (or very little) current flowing through the circuit. But once placed under load (such as trying to engage the starter), the additional current flow across the bad (high resistance) connection creates a large voltage drop that prevents things from working.
To see if that is the case, start by re-checking the voltage on the red wire that feeds battery power to the ignition switch. But this time, also turn the key to the start position while checking the voltage. If the voltage drops way down on the red wire when trying to crank the engine, that is a good sign that the bad connection is somewhere in that wire. With the help of a wiring diagram, you should be able to trace it all the way back to the battery and check for bad connections along the way.
If the red feed wire checks out okay (no / minimal voltage drop), move on to checking the purple wire that runs from the switch to the starter. Note that if your truck has an automatic transmission, there might be a neutral safety switch in the circuit. If so, be sure to check that too.
As far as grounds are concerned, there is only one ground wire that is necessary to make the starter operate. And that is the negative battery cable that should have a good connection to the engine block.
The body of the ignition switch is grounded to the truck's metal dash. And when the key is turned to the start position, it temporarily grounds the white wire which runs to the "hot" light on the dash. That completes the circuit to ground for that light, making it illuminate while cranking the engine. It's a "bulb test" feature so the driver will know the bulb isn't burned out. But it has absolutely nothing to do with making the starter operate.
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Thanks! That is a very thorough response. Supposed to be nearly 60 here tomorrow, I'm going to spend most of my day working on it. There are only 3 parts and like 4 wires. I have to be able to figure that out.
BTW, if you have a minute, any thoughts on what I'm doing wrong with the key?
https://www.youtube.com/watch?v=dMlCHFoUndg
Oddest thing I've experienced trying to get it out.