TJ occasional no start

[rob@fain]

Hello all,
My 2003 TJ won't start no crank, I can disconnect the negative battery terminal and reattach and it starts right up. This happens about every 3 or 4 months.

Could this a PCM issue?

 

[macleanflood]

@Wranglerfix

www.wranglerfix.com for replacement or PCM repair.

I couldn't see how a 3-4 month intermittent issue would be the PCM...but Mark might have a clue.

Have you checked wiring? Cleaned battery terminals and grounds? How often do you drive your TJ? How old is the battery? What's the battery voltage at rest...when you try and crank it and it doesn't start what does the battery drop to?

-Mac

 

[hear]

Hello all,
My 2003 JT won't start no crank, I can disconnect the negative battery terminal and reattach and it starts right up. This happens about every 3 or 4 months.

Could this a PCM issue?

Are you sure the negative is actually seated well when you perform this fix? It's not the act of removing it that clears the issue, it's the act of re-seating it to make a better connection. That's my guess anyway. I'm pretty lazy about tightening my negative cable since I'm constantly removing it to work on stuff. Every now and then it must work just loose enough and it won't crank over. Usually just bumping it with the heel of my hand is enough to fix it.

 

[rob@fain]

@Wranglerfix

www.wranglerfix.com for replacement or PCM repair.

I couldn't see how a 3-4 month intermittent issue would be the PCM...but Mark might have a clue.

Have you checked wiring? Cleaned battery terminals and grounds? How often do you drive your TJ? How old is the battery? What's the battery voltage at rest...when you try and crank it and it doesn't start what does the battery drop to?

-Mac

It's a daily driver, battery terminals are clean and well connected. In the past I thought it was the clutch safety switch which bypassed, I've changed the ignition switch.

 

[Wranglerfix]

Hello all,
My 2003 TJ won't start no crank, I can disconnect the negative battery terminal and reattach and it starts right up. This happens about every 3 or 4 months.

Could this a PCM issue?

It could be… Are you getting any codes?

 

[Harold&Cat]

When you say " no crank " , are you referring to nothing happening such as the engine not turning over ?

If so , I didn't think the ECM could stop the starter from turning the engine over .

Possible problems :
Bad starter
Bad solenoid on the starter
Bad ignition switch
Bad battery cable connections
Bad neutral safety switch or clutch safety switch
Short in starter wire

 

[rob@fain]

It could be… Are you getting any codes?

No codes, lights come on everything seems good but no crank.

 

[rob@fain]

When you say " no crank " , are you referring to nothing happening such as the engine not turning over ?

If so , I didn't think the ECM could stop the starter from turning the engine over .

Possible problems :
Bad starter
Bad solenoid on the starter
Bad ignition switch
Bad battery cable connections
Bad neutral safety switch or clutch safety switch
Short in starter wire

Correct, lights come on but the engines doesn't crank.

I changed battery, starter, ignition switch and bypassed the clutch safety switch.

Every other time this has happen, disconnecting and reconnecting the battery made it work. That's why I'm thinking PCM.

 

[Harold&Cat]

Correct, lights come on but the engines doesn't crank.

I changed battery, starter, ignition switch and bypassed the clutch safety switch.

Every other time this has happen, disconnecting and reconnecting the battery made it work. That's why I'm thinking PCM.

Read through this thread . It says there is a starter relay . It could be a problem in that circuit or the relay itself .

https://www.google.com/url?sa=t&sou...CCMQAQ&sqi=2&usg=AOvVaw0TIaPMr3HKYocHR01kGUM4

 

[hear]

I don't know how unplugging the battery would correct a relay issue, but just swap the starter relay with a known good relay from the PDC and see if anything changes.

 

[Harold&Cat]

It could be… Are you getting any codes?

Is there a circuit that the PCM controls that would not allow the starter to turn the engine over ?

I was aware of this in the newer Jeeps , but not on our TJ's .

 

[rob@fain]

Read through this thread . It says there is a starter relay . It could be a problem in that circuit or the relay itself .

https://www.google.com/url?sa=t&sou...CCMQAQ&sqi=2&usg=AOvVaw0TIaPMr3HKYocHR01kGUM4

I'll check the wiring and the relay. The problem only happens about every 6 months. Taking the negative terminal off for a few seconds is the easy fix, but I would like to know what's really going on.

Thanks for the insight.