The battery is a new Optima and it’s not the problem.
Sniper control panel shows 12 v in the run position.
We've said it here many times. New does not mean good.
Granted, your new battery is low on the list of suspects, but keep it in the back of your mind anyway. As they say, trust, but verify.
And does it say just 12v? Or does it say 12.5 or 12.6 volts? A fully charged battery is something like 12.6v so if it's not reading that, it has been at least partially discharged and you might want to put it on the charger anyway.
My first thought was the neutral safety wiring so I’ll check that.
Good plan. Since you get nothing, no click or anything, it's a good bet that the signal to start is not making it to the starter relay.
But go ahead and run down your relay bypass tests.
Obviously, for all of these tests the transmission should be verified in Park or Neutral. With any tests that the key does not have to be ON or in START, verify that the key is indeed in the OFF position.
First thing to check, even before doing the bypass tests, is to put a volt-meter on the small Red w/blue wire (If an aftermarket harness it could be Violet/Purple) from the "S" terminal to see if it's getting 12v from the key.
Easiest way to do it is with a helper. Pull the wire off the stud, and with the helper holding the key in the START position take your voltage measurement. Should be pretty close to full battery voltage.
If not, then your problem is upstream, somewhere between the ignition switch, the wiring, the NSS and the wiring.
If you do get voltage at the wire, then on to testing the relay...
1. While the key is OFF and the Red w/blue wire is still off of the relay, jumper between the large post on the left with the battery cable, to the small "S" post. You can use a small wire of 14ga or larger, with the metal handles of a pair of pliers, or just a screwdriver if you can do it without shorting it to the body!
If you had voltage at the small wire but no cranking, and now with the jumper the starter cranks your relay is good, but you have a bad connection right there at the Red w/blue wire.
If the jumper trick does not even give you a big healthy click at the relay (whether the starter cranks or not), then either the relay is not properly grounded, or your relay is defective and needs to be replaced.
If it clicks, but still no starter activity, on to the next step.
2. With a heavier duty tool, such as jumper cables or a heavy duty large pair of metal plier handles, jumper the two large terminals on the starter relay together. This essentially bypasses the entire relay and connects (theoretically) your starter to your battery directly.
If the starter cranks, you may still have a bad relay. It could be clicking, but not making full contact inside.
If still no cranking, then you have either a bad starter cable, or a bad starter. Try hitting the starter as suggested above.
3. With the jumper cables and a VERY careful attitude and method, jumper the starter directly to the battery. Clamp to the starter first, then touch the other end to the battery.
If it cranks you have a bad connection, or a bad starter cable.
If it does not crank, your starter is bad. Of course, if you hear anything at all from the starter, or the cables get hot immediately, this is the time to make sure your engine can at least turn over. Crank the engine by hand just to verify. It's rare, but it's happened that an engine is locked up for one reason or another.
The above is if you have a standard Bronco starter. If you're using a modern PMGR or mini-type starter, the method will change slightly.
Those are most of the main steps. If I left anything out the others will fill in the blanks. But it gives you a basic rundown of the system and things to look for.
Naturally, if it fails the first test and you have no voltage at the Red w/blue wire (or as mentioned, perhaps Violet/Purple) then you move upstream and test the input/output of the NSS wiring. With your 4R70 it's not just a simple 4-wire plug with only two colors to deal with, so others will have to chime in with some details of that.
But you can check the ignition switch very easily too. If power is coming in on the Yellow wire and is going out on the Red w/blue wire in START, then the issue must lie somewhere in-between.
Paul
