Starts when you let off the key.....

[wally426ci]

Moparts threads seem to lean toward a faulty plug end somewhere needing some clean up. I figured that I would avoid the negativity and come straight to here. Anyone else ever deal with this?

Electronic ignition small block 71 Challenger..... 

 

[Bullitt-]

it's either a bad ballast(if you have a 4-prong) , ignition switch or wiring from the switch that powers the ignition system in the start position

[Chryco Psycho]

typically a bad ballasst , change that out first

[dodj]

it's either a bad ballast(if you have a 4-prong) , ignition switch or wiring from the switch that powers the ignition system in the start position

My money is on the ballast. If not that, the column connector or the bulkhead connector.

[72rtchallenger]

   leaning towards the ballast too as we all have seen them do that

[wally426ci]

Thanks guys, Im running a 2 prong, but i will change it out anyway since i have an extra. Hope its not column wiring since I hate having to break that all apart!

[UKcuda]

Thanks guys, Im running a 2 prong, but i will change it out anyway since i have an extra. Hope its not column wiring since I hate having to break that all apart!

If it's a two prong ballast I'd say it can't be the cause as it is completely by-passed in start position and only comes into the equation when you let off the key, which is when yours is OK.

[GoodysGotaCuda]

Thanks guys, Im running a 2 prong, but i will change it out anyway since i have an extra. Hope its not column wiring since I hate having to break that all apart!

My 2-prong did that when it failed.

[ShelbyDogg]

I think it is the faulty plug end somewhere at the ignition switch connector or the bulkhead connector. Disconnect your yellow wire on the starter relay, so it doesn't crank. 
Use a test light on the brown wire on the ballast resistor and check for light in the start position.
Follow it through the bulkhead, then the connector to the switch connector. Brown wire all the way to the switch. Something isn't lighting the light.

If it was a bad 2 prong ballast, it would start in the start position, then die in the run position.

[OUTLAW]

Usually when the ballast goes it starts in crank and dies when you release the key. Sounds to me like no power to ignition UNTIL you release the key ...my moneys on the ignition switch first then the bulkhead conector.
Easy enuff to find out... put a test light on the battery side of your ignition and watch it while you crank it ... no light until you release the key...ignition switch

[wally426ci]

Doh! Looks like maybe i could need a switch soon. Thanks for all of the tips! I wont get a chance to work on it for at least a couple months since we are moving, but hopefully it will stay running that way for now.

[dougs bs23]

good luck with the move.... staying in md?

[wally426ci]

good luck with the move.... staying in md?

Well.....yes, we actually pulled out of the contract after the home inspection so we are staying put until Spring at least...... I may get some wrenching time before the baby gets here!

[cwestra]

I just had the same thing happen to my car.  I pulled the trans to do some work and when I reinstalled it and tried to start it it would not stay running after I released the switch.  I don't believe it's the ballast resistor because when I jumper it between the 2 prongs (with plug wires still connected) it still has the problem.

A jumper from the positive terminal of the battery and the single wire connector on the ballast does get the car running.

I have approximately 12.5 v on both prongs of the ballast when cranking and 0 when released.

After reading the tread above it looks like the switch may be the issue but I can't understand why it would have happened right after R&R of the trans.  Seems odd to me.

Is it possible that the ECU in the electronic ignition system could be a source of the problem as well?

[tman]

In your case since you removed the trans, check your neutral safety switch.  If its an auto, make  sure  shifter  is adjusted right.  Will it start in "neutral" or "park"?   Can't help with manual shift.