Ignition key problem?

If the terminals are discolored from being overheated, there is no way to know if that started in the old switch or in the terminals. Most of the time it starts in the switch, then the heat migrates out to the terminals. The clue is it affects both of the pairs of terminals. If the heat build-up started in between one pair of terminals, it is unlikely that heat would make it to the other pair of terminals and that wire.

Regardless of where the heat problem started, the terminals and the switch must be replaced, because leaving either one in place will cause the problem to keep on occurring.

You can replace the entire connector if you want to, but to make the job go faster, I would only cut off the two wires with the overheated terminals, and splice them to the new connector. If you pull out the locking wedge, (usually red plastic), it will allow you to lift the plastic fingers that let the terminals be pulled out. Those that are nice and shiny yet can be transplanted into the new connector body. That will save you cutting and splicing wires that have nothing wrong with them.

I assumed when you replaced the ignition switch, it was a used one from the salvage yard. With the three different designs, the lock cylinder must match the switch, but once the cylinder is installed, that entire switch assembly can be interchanged with any of the other designs. That means you could have installed a switch that originally came in a minivan. For the problem you described, that broken disc was the most common cause, and it was an easy fix. I ran into this four times. Once on my mother's '95 Grand Caravan, twice at the dealership, and most recently, last summer on my '94 Grand Voyager daily driver. Coincidentally, the switch I put in my van came out of an early '90s Jeep.

Jeeps used a lock cylinder with what looks like a "T" on the end. It sits in two notches in the rotating part of the switch. I've never seen one of those break, so when you mentioned that, my first assumption was someone already replaced it years ago with the minivan-style switch. The easiest fix is to just unbolt one in the salvage yard and bolt it into your vehicle, and use the keys that came with it, as I am doing. If you want to keep your original keys that match the door locks, you have to find a replacement switch for a Jeep, then transplant the original lock cylinder into it.

Now that you said the ignition switch is new, if the old one had burned terminals, you only have to replace those two terminals yet. The switch half of the job is already done. As I mentioned previously, that starter circuit part of the switch is less likely to develop this problem, but if the switch is new, the reason 12 volts is not making it to the starter relay has to be a wiring issue.

Check for 12 volts on the red / white wire, (A1 12RD/WH), in the switch's connector. It should be there all the time. If it is missing, we'll have to work back to see where it is being lost. If you do have 12 volts there, but not on the yellow / dark blue in the "crank" position, there has to be a problem with the switch.

The only other thing I can think of is when you removed the lock cylinder, there was a roll pin that had to be pushed in about 3/16". When the cylinder is installed, that roll pin gets pushed back out the first time you turn it to the "crank" position. Pushing that pin out requires higher than normal force which might lead you to believe the switch has been turned as far as it should go. Most of the time this added force isn't really noticeable, but to insure this isn't the problem, turn it a little harder to see if the starter engages.

Hold on. I think we're mis-communicating due to a problem with terminology. In your title, you listed, "vehicle cranks but does not start". In the first post, you said, "Turn key on dash lights work no crank", then all the tests you listed involved the starter system not working. In your reply from last night, you said, "it wont start anymore but it still cranks." That agrees with your title to this question, so you can see my confusion.

I've been thrown for a loop in the past when someone said they "cranked the engine", meaning they turned the ignition switch to the "crank" position. Then they added, it doesn't start", meaning the starter doesn't spin the engine. The term, "doesn't start" has always been a point of confusion that is often aggravated by radio commercials. To be sure we're talking about the same thing, I use the symptom description "crank / no-start" when describing the starter spins the engine, but the engine doesn't run, or I avoid using "doesn't start", and use "cranks, but doesn't run".

Another one is "turns over". Some people think that means they turned the ignition switch. "Turns over" means the starter is cranking, or turning, the engine. In an attempt to avoid this confusion, some of my replies become somewhat cumbersome or wordy, but it insures I'm thinking of the correct set of symptoms.

After rereading your comments a few times, any time you say the starter cranked the engine, please be sure to make clear whether that was by turning the ignition switch to "crank", or by jumping the two terminals at the starter or by doing something at the starter relay.

Now that I got that out of the way, last night you said, "it wont start anymore but it still cranks". Do you mean the engine is spinning when you turn the ignition switch to "crank", but it won't run? If so, try that while holding the accelerator pedal down 1/4". If that gets the engine running, there's an easy fix for that. I'll describe that later to avoid more confusion now.

Earlier today you said, "nothing on the blue/yellow in the crank position". If the starter engages when you turn the ignition switch to "crank", there has to be 12 volts on that blue / yellow wire. Where I usually make the mistake is not getting the probe in far enough or at the correct angle to touch the terminal.

Rather than wait for your next reply, let me jump ahead as it is starting to sound like the new switch has a problem. I see what you mean about the yellow / dark blue wire. It is in one of the two smaller holes. You might have better luck sticking a straightened-out paper clip in there. You have the correct two terminals, those on each end of the connector. A quick way to verify the switch is at fault is to jump those two wires together right there at the back of connector. You can do that with a pair of paper clips or a piece of wire. The engine should crank, but it won't run as long as the ignition switch is off. If you want the engine to run, turn the ignition switch to the "run" position, but be sure the transmission is in "park". We don't want you to look funny chasing after the vehicle as it drives away.

Oops; it just occurred to me the starter still won't engage unless the neutral safety switch is in the "park" or "neutral" positions. I'm ignoring that entire part of the system for now because your previous tests at the starter relay socket showed that to be working.

If you can't get the starter to engage by jumping those two wires, pull the connector off, then try again by going right on the terminal end with the paper clip or piece of wire. Now if the starter engages, either the new switch is defective or one of those two terminals is spread open too far to make contact with its mate. When a terminal is spread open, you can often get the circuit to work momentarily by tugging on the connector to bend it a little. That can move the spread terminal just enough for it to make contact.

Let me know what happens when you jump those wires.

This is not common, but it sure sounds like the switch is defective.

Once you get that replaced, the failure-to-run problem could very likely be due to idle speed is too low. This happens if the battery was disconnected for some other service. When that happens, it will run if you hold the accelerator pedal down 1/4".

The Engine Computer lost its memory and will relearn sensor personalities and fuel trim data as you drive, without you even noticing. "Minimum throttle", on the other hand, needs a very specific set of conditions for the computer to know your foot is off the accelerator pedal, then it takes a throttle position sensor reading and puts that in memory. From then on, any time it sees that voltage, it knows it has to be in control of idle speed.

To meet the conditions for minimum throttle to be relearned, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

Dandy. Happy to hear you solved this. Please come back to see us again.