97 Wrangler need to hotwire/bypass pcm emergency start needed - Jeep Wrangler Forum

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Old 05-09-2013, 07:07 PM   #1
Falcho's Avatar
Join Date: Jun 2012
Location: North Pole, Alaska
Posts: 52
Exclamation 97 Wrangler need to hotwire/bypass pcm emergency start needed

Hi kids of all ages,
I have a friend, who has a 97 wrangler, 4.0 auto. He lives very remote in the bush here in Alaska. The battery ran dead on it, and when replaced, the infamous no start no gauge no check engine light happened. the CPS and the other usual suspects have been checked with a no go. Theres no way short of an air lift thats going to get this jeep out of where its at, unless we can get it to start. So, we need the info to hotwire this bad boy to bypass all the evil the pcm is doing. Not worried about what accessories work or not, just that it starts so we can get it to a road to trailer it back to town. Does anyone know a quick and dirty way to get this bad boy fired up? Dont want to have to do more then the absolute minimum to get it out so as not to compound problems. Help us Obi Wan Kenobi, your our only hope! Or, any of you other jeepers out there
Any help would be appreciated. Thanks in advance

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Old 05-09-2013, 07:48 PM   #2
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Join Date: Jun 2007
Location: Goldsboro, NC
Posts: 283
Turn key to run, then jump the starter from power to signal. Not 100% that will work.

1997 Jeep TJ -- 5.3L LM7 - NV3550 - More to come..
2001 Chevrolet Silverado -- 6.0L LQ4 - 4L80E
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Old 05-09-2013, 09:07 PM   #3
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Location: California/Nevada
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You are going to have to find out why it is not getting power. What caused the battery to run down?

Have you checked all the fuses in both places (PDC & fuse block)? What happens when you turn the key? Anything in the cluster work or gauges move? Got headlights, wipers, radio? Make sure the cable from the B+ post to the PDC is good both at the battery & the bolt where it attaches to the PDC. See if fuse #3 in the PDC is good. Then pull it & verify it has 12v at one terminal. That is the main power source to the ignition switch.

Any other info you can think of might help.

'05 Rubi TJ Unlimited
'93 Toyota 4Runner
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Old 05-10-2013, 09:19 PM   #4
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Join Date: Jan 2013
Posts: 108
I'm not aware of any way to bypass or Hotwire the PCM.....however, when my 97 experienced major "brain farts" I found that you can run a jumper wire from the ground on the ASD relay to the ground on the Fuel Pump relay and in many cases force the PCM to accept the situation at hand and let the engine start and run.

Before you try this, disconnect BOTH battery terminals for at least a minute. WITHOUT a battery in the loop, touch the positive and negative cables together for about 15~30 seconds. This will reboot the PCM and it will go into its relearn stage. I cannot emphasize enough that you must not have ANY connections to your battery when doing this.....NONE!

This hasn't always worked for me, but it has not hurt anything to try it.

The PCM sends ground signals to activate the relays, the 12v power is already there. The fuel supply will energize before the ASD can go to default and since the PCM supplies separate ground signals, you're just kinda making sure everybody's there and ready to play the game.

Best of luck
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Old 05-10-2013, 09:22 PM   #5
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Posts: 108
Sorry, meant to show the ground terminal

-- < ground
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