donjames2009

true .... no start without it ... for sure. He will have to wait until he gets the trans back in to run down the starting problem. Got focused on the wiring problem and didnt take a look at the bigger picture.

This goes without saying but you have to be certain that the relay is actually working BEFORE starting the rest of the diagnostics that I will describe. You can easily pull another relay in the Power distro panel from a known good circuit and swap it out as a quick test. Be advised that the circuit will not work with the trans removed unless you follow the method that I outlined below .... see paragraph three below for detailed instructions on by-passing the PRNDL switch. There are two sides to the relay (its more or less the middle of the circuit for the starting system). Its the key area for proper diagnosis of your issue. There are two things to test for the power supply at the relay that is located in the power distribution center. Look for both of these at the connectors that the relay plugs into (use a 12v test light) .... 1. intermittent power to one of the terminals when you actually turn the ignition switch to the start position .... 2. Constant power to a different terminal. If you have both of these power sources to the relay socket, your problem is on the downstream side of the relay. If you are missing one of the two, your problem is back to the 12v source. Let me know if this is the case and I will tell you how to pinpoint the source problem. There are two sides to the downstream portion of the starting circuit from the relay. The first provides the ground path for the 12 volts provided by the ignition switch. This circuit follows a black (with a white trace) wire down to the left side of the trans. It passes into the Park/Neutral switch and then grounds. This will only happen if the vehicle is in Neutral or in Park. You can test this with the trans removed by finding the wire by color and providing a temporary ground back the the engine (a jumper wire). If the transmission were in the truck you would still diagnose in the same manner in order to insure that the P/N switch is providing the proper ground path. No ground path .... bad switch. The second path goes directly to the starter itself. Its a brown wire that energizes the solenoid that is on the starter. Be advised that this same source of power also connects into the Fuel Shutdown Relay via this same brown wire. When you apply power to the starter solenoid it simultaneously sends power to the relay that energizes the fuel shutdown solenoid that allows to fuel to flow to the engine. It flashes power to the relay which causes the solenoid to pull the arm connected to the fuel metering rod up. You will here a loud click / thunk when it actually works. This not happening (if there is a break in that wire or a problem with that relay) will allow the vehicle to crank but not start. Let me know what you find out with your diagnostics. We can go further if needed. One word of caution ... starting the engine without the trans in might not be a great idea unless you brace the backside of the engine first. Use a floor jack or something to lift the motor back into the right position prior to running the engine. Good luck!

Is your truck a standard or auto trans? Just to clarify .... the truck will not crank and you have tested it at the solenoid (small wire on the starter) and you have no power ... but you have power on the main feed (big red wire) going to the starter?

hello, I am new to your site but very surprised to find it. I am a die hard Dodge truck owner. Currently own a 97 2500 with the Cummins diesel. Retired army. Living in Florida. I have been having wiring issues with my truck for a while now. Have had to trouble shoot most of my electrical problems the hard way .... via half-baked wiring diagrams, VOM, and text light .... in the past. I am currently working on a problem concerning my A/C not working. I think that it is the climate control switch but cannot tell which wire actually feeds the signal to the PCM to tell it that the A/C is on (I am assuming that is required and that the PCM is monitoring the low / high pressure switches and temp control of the system). Having a wiring diagram ... or at least one that shows more than the headlight layout (lol .... chiltons manual) ..... would be a great help. I tried to download it twice and received an error due to not being a member long enough. Any help would be greatly appreciated. I look forward to communicating with you in the future.