Possible to fry the computer without blowing a fuse?
Thread Starter
Member
Joined: Nov 2008
Posts: 142
Likes: 0
From: Indiana
Year: 1987
Model: Cherokee
Engine: 4.0
Well, in the ongoing search for why my wife's Jeep won't run (other posts on here), is it possible that the computer fried from where the O2 wires were dangling (cat had been stolen) but didn't blow a fuse?
CF Veteran
Joined: Mar 2009
Posts: 28,068
Likes: 6
From: Tenn. and Mich.
Year: 2004
Model: Grand Cherokee
Engine: 4.7L V8
Try checking for any stored trouble codes yourself like this: http://jeephorizons.com/phpbb/viewtopic.php?t=2719
Turn the key on, off, on, off, on, off, then on and the digital odometer will start showing any codes. If no codes are stored it will show 55, which is End of messages, no codes stored. Codes disappear after 50 key starts if there's no reoccurence of the problem.
You can erase any codes after repairs by disconnecting battery cables and holding them together for 15 seconds to drain any residual charge, and codes, in the PCM. Then reconnect the cables and drive normally for a few miles so it can relearn the system parameters.
Or you can go to any auto parts/repair facility and they can check the codes and clear them if needed.
Thread Starter
Member
Joined: Nov 2008
Posts: 142
Likes: 0
From: Indiana
Year: 1987
Model: Cherokee
Engine: 4.0
Yeah no codes showed up. But the battery had been out for a while to charge, so it also gave me 12 (codes reset/power loss) and 55. I guess the dealership can't check the computer (checking if its bad or good) without it being in the vehicle. For the cost just to pull it in to their center, I can buy another unit which is probably what I will do, just in case. It's sending the right voltage, but it's not getting proper spark.
CF Veteran
Joined: Nov 2010
Posts: 15,581
Likes: 8
From: some small town oregon
Year: 1989
Model: Cherokee
Engine: 4.0
im gonna say yes it is possible to kill an ecu without poping a fuse.
while wheelin in my 97 grand i ripped out the o2 wires they touched and the jeep died..i tried all the easy stuff first relays cps ect..(mainly cause there where no ecu's around) but one day found one and it started right up
while wheelin in my 97 grand i ripped out the o2 wires they touched and the jeep died..i tried all the easy stuff first relays cps ect..(mainly cause there where no ecu's around) but one day found one and it started right up
Thread
Thread Starter
Forum
Replies
Last Post
jmsummers2012
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
56
Jun 12, 2025 02:04 AM
LittleRed94
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
5
Oct 6, 2015 08:09 PM
tleed
Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!
3
Oct 4, 2015 01:20 PM
xjcarolina
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
5
Sep 29, 2015 08:43 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)



