2012 JK No-Crank Gremlin Mystery

Mark B

Mark B

New Member
Joined
Jul 24, 2021
Messages
8
Location
Fort Collins, Colorado
I have an intermittent no-crank issue that I have not seen a forum discussion thread discuss. Very intermittently, my 2012 Wrangler will not crank-over and is completely dead. Sometimes it seems to be associated with heat buildup, such as on a hot day after stopping it. At other times, it has happened when 4-wheeling and I've done an ascending climb and stall it with my manual transmission. After other times, it is from a cold start in my garage. It does seem to occur more in warm outdoor temperatures rather than cold outdoor temperatures. In most cases, I can restart it eventually after a few minutes or if I move the vehicle a bit forward or backward. In any case it is unnerving when it happens while 4-wheeling in remote locations. The occurrence is very intermittent and occurs about once every couple of months. My battery has been replaced and my battery cables/connections all look in decent condition. Thoughts out there?

Mystery in Colorado...
 
Is there a little red light in the dash cluster on in the upper right top?

Have you tried putting it in 4 low to see if it would start?
 
You say it is "completely dead". By that do you mean that nothing has power when this happens? Or do the dash lights come on?
 
When it does this, it is completely dead with no dash lights or crank. The last couple of times it has happened while wheeling in 4-Low, I have got the lights back and started it, albeit with some cranking effort, by rolling back about 5 ft and then re-trying it. The few times it has happened when I was not in 4-Low such as my garage, I have not tried putting it in 4-Low and trying to then start it.
 
Dirty Dog said:
You say it is "completely dead". By that do you mean that nothing has power when this happens? Or do the dash lights come on?
Click to expand...
When it does this, it is completely dead with no dash lights or crank. The last couple of times it has happened while wheeling in 4-Low, I have got the lights back and started it, albeit with some cranking effort, by rolling back about 5 ft and then re-trying it. The few times it has happened when I was not in 4-Low such as my garage, I have not tried putting it in 4-Low and trying to then start it.
 
BLACKJKU said:
Is there a little red light in the dash cluster on in the upper right top?

Have you tried putting it in 4 low to see if it would start?
Click to expand...
When it does this, it is completely dead with no dash lights or crank. The last couple of times it has happened while wheeling in 4-Low, I have got the lights back and started it, albeit with some cranking effort, by rolling back about 5 ft and then re-trying it. The few times it has happened when I was not in 4-Low such as my garage, I have not tried putting it in 4-Low and trying to then start it.
 
Do you still have the Factory battery clamps on? If so replace them with a good set of clamps.
 
The battery clamps, cables, and ground connections are all original stock. You think this could cause the intermittency and have an association on a 4WD Low stall?
 
Bad grounds, dirty battery clamps and posts, and junk Factory battery clamps can cause all kinds of electrical issues.
 
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Mark B said:
The battery clamps, cables, and ground connections are all original stock. You think this could cause the intermittency and have an association on a 4WD Low stall?
Click to expand...
You said it happens when it's not in 4-Lo, so I'd say don't obsess on that. Correlation is not causation. Causation is, generally speaking, consistent.

The Jeep Wrangler battery terminals are complete junk. And there are 14,873,291 grounds, any one of which can cause things to die when contact fails.
 
What they said^^^ about grounds . As great as the Jeep is off road it can be hyper sensitive to a bad ground or electrical glitch somewhere .
Whenever I’m leaving a trail and about to go on main road .I always check turn signals , brake & headlights as the vibration off road can cause a connection or something to loosen up.
It is interesting that if you roll it back 5 feet you be can get it to turn over & start. I’m wondering if possibly starter related but you also mentioned initially everything dead .
That rolling it back to make it work is a bit baffling .
 
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OK, thanks for the insights. I think I have a path forward to start troubleshooting this.
Speartip said:
What they said^^^ about grounds . As great as the Jeep is off road it can be hyper sensitive to a bad ground or electrical glitch somewhere .
Whenever I’m leaving a trail and about to go on main road .I always check turn signals , brake & headlights as the vibration off road can cause a connection or something to loosen up.
It is interesting that if you roll it back 5 feet you be can get it to turn over & start. I’m wondering if possibly starter related but you also mentioned initially everything dead .
That rolling it back to make it work is a bit baffling .
Click to expand...
 
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