Jeep Won’t Start After Flat Tow

Dreamer Easy

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I have flat towed behind my motorhome 9 times. 4 of those times the Jeep failed to start after being towed. Any idea why?

Additional information: Automatic Transmission, V6.
Each time the Jeep was placed into and taken out of recreational towing mode I followed procedures described on pages 397–402 of the 2019 OM.
At the end of the procedure to place the Jeep into tow mode, the START/STOP Ignition Button was left in the OFF position. It was not left in the ACC position while being towed.
There was no rapid clicking associated with a dead battery when the Jeep would not start. The battery was checked with a voltmeter and found to be fully charged. I simply put my foot on the brake, punch the START Button and nothing happens.
Troubleshooting to isolate: without connecting the Jeep to the motorhome, I placed the Jeep into tow mode and then took it out of tow mode the next day. The Jeep started every time. I must have done this 8-10 times. The problem only occurs after the Jeep has been towed behind the motorhome, the last time being after the troubleshooting to isolate the problem.
The only electrical connection between the motorhome and the Jeep is a 7-wire power cord that operates the Jeep’s left/right turn signals, brake lights, and taillights.
The charge line on the 7-wire power cord was checked and found to be providing proper voltage from the motorhome to the Jeep battery.
None of the 3 different Jeep dealerships that have investigated the problem have been able to replicate the problem or find anything wrong.





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zb39

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operator22

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Most auto transmissions won't start if the logic say it is not in park or neutral. In some cars, the brake pedal must be depressed. Haven't taken my JL delivery yet so these are just ideas.
 

four low

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If you use a jumper to bypass the Aux battery ( great thread on this ) will it start ? The " IBS " might not be sharing the charging voltage to the Aux battery, when not coming from the Jeeps alternator ?
 
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Dreamer Easy

Dreamer Easy

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Most auto transmissions won't start if the logic say it is not in park or neutral. In some cars, the brake pedal must be depressed. Haven't taken my JL delivery yet so these are just ideas.
operator22, congrats on the new JL! My advice is to have the dealer go over getting in and out of tow mode with you. My "not starting" issue aside, you'll be surprised at how stiff and uncooperative the transfer case is. But that's a topic for whole other thread.
 
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Dreamer Easy

Dreamer Easy

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If you use a jumper to bypass the Aux battery ( great thread on this ) will it start ? The " IBS " might not be sharing the charging voltage to the Aux battery, when not coming from the Jeeps alternator ?
Thanks four low. I haven't tried the jumper but I think I found the thread you mentioned so I'm going through that.

Interesting thought on the IBS not sharing with the AUX battery. I'll check with my dealer's service department since they Jeep at the moment. I'm also going to call Roadmaster, the company that provided the power cord from coach to the Jeep to see if they've ever heard of this problem. They provide towing for lots of Jeeps. And we'll check to see if the IBS is actually providing power to the AUX when I get the coach and Jeep together again.
 
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Nutmeg

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If your using an axillary braking system that bleeds the vacuum can down, I have found you have to press extra hard on the brake for the first start up after towing.
 

Nutmeg

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In regards to shifting the transfer case in and out of neutral, in does seem to get easier over time. Coming out of neutral is more of a challenge on mine than going in. On mine if it does not go right in, I will start the engine. place trans in reverse for a second then shut down and try again. Thought is it is spinning the gears to get a better alignment but only shifting the transfer case with engine off.
 

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