Topic: No spark part duex

[Raistlinalpha]

I had posted this problem a few months ago and you guys had all given me some sound advice but I still have no spark. Here is the story...

95 YJ automatic

I put a new o2 sensor, recharged the k&n filter and sprayed the alternator with an electrical cleaner. It fired right up and I let her run for a little bit then shut it down. The next morning I went to move it in the barn and it would crank and crank but no fire.

This is the list of things I have replaced (all new) in search of the problem.
Crank position sensor
electronic pick up plate
distributor cap
rotor
coil
map sensor
Auto shut off relay
ignition switch
alternator (it was bad)

I am getting one spark when you turn the key to on position and another on the first crank. Then nothing until you turn the key back to off, which then a spark is thrown when the switch goes through the on position. I had taken it to a local garage and the mechanic told me everything is throwing the correct signal, it just will not throw a spark. He suggested the ecm (he told me it was a guess and could not guarantee it was the answer). I sent the ecm off to be refurbished and it returned clean and half the price I was originally quoted. Napa had no idea why it was cheaper and I didn't complain about it. This did not fix the problem. He suggested an auto electrician he knows, I decided to take it to the club garage. It has stumped everyone there.

I had taken the distributor out to install the new pickup plate. We have turned it 180 out in case I jacked the timing with that installation, no go.

The starter appears to be new and I was told it was new when purchasing but...you know how that goes. I am getting the correct reading to the coil.
The fuel pressure is good.
We have traded relays and by-passed the relay with no affect.
We have bypassed the ground on the coil along with trying different coils, nada.

I have not tried the neutral safety switch but I would believe it wouldn't crank if that was a problem plus the mechanic told me it was good.
In the previous thread I was told to run a series of tests to check the ecm and it was coming back positive, this was before the mechanic guested it could be a problem and before sending it off.

We are now waiting for a used ecm which will be delivered this Tuesday to toss it in on Wednesday night.

Any thoughts or opinions?

[Bounty Hunter]

I am getting one spark when you turn the key to on position and another on the first crank. Then nothing until you turn the key back to off, which then a spark is thrown when the switch goes through the on position.

Sounds like maybe a bad ignition switch in the column, or something to do with it.

[aw12345]

Since it gives a spark when you cycle the key, seems to me it has power to the coil, I would look down stream from the ignition coil , I would also make sure the auto shut down relais activates. Actually the first thing to check with use of a scanner would be to see if you can see cranking rpm on the scanner while crancking. If no acces to scanner crank it and see if the auto shut down relais activates, if it does that means the ecm is seeing cranking rpm, my guess is that that relais is not activating. If not you will have to follow the power from the negative side of the coil to the ignition module, to the crank sensor and what ever else is in that circuit.

[Raistlinalpha]

I will check into both of your suggestions this coming Wednesday night. I have no problems double and triple checking everything I have done.

[Raistlinalpha]

I am celebrating the one year anniversary of my YJ not running. Thankfully it is an extra vehicle. We kept the jeep in our club garage for months and had numerous people stop by to offer suggestions. Nothing worked. I finally had it and we yanked the entire drive train out of the damn jeep. The jeep is completely torn down and I am starting from scratch. I am just about finished with a body lift and will begin putting it back together. I am doing away with all the electrical crap in the bugger and going old school. I am leaving the 4 banger world and dropping in a 258 out of an 80 waggy. I hope to have it on the road this spring, but who knows.

Every once in a while, we will be hanging out in the club garage and one of us will bring up the mysterious YJ that just wouldn't throw a spark.

[VA_YJ]

I had problems with my wiring harness.  The connectors have pins that contact (or don't contact) sleeves.  I found my problem by moving wires until I found the bad connection.  It turned out to be the connector to the coil (two pins).  I fixed it by squeezing the sleeves with a pair of pliers to get better contact.  I have a nephew who is a certified mechanic.  He says this is common problem with Chrysler products.  My advice is to check your harness connections carefully before buying more parts.

[sharpxmen]

I had problems with my wiring harness.  The connectors have pins that contact (or don't contact) sleeves.  I found my problem by moving wires until I found the bad connection.  It turned out to be the connector to the coil (two pins).  I fixed it by squeezing the sleeves with a pair of pliers to get better contact.  I have a nephew who is a certified mechanic.  He says this is common problem with Chrysler products.  My advice is to check your harness connections carefully before buying more parts.

he took the entire drivetrain out so he won't be troubleshooting that problem no more (he's replacing the motor)