CheepComanche Posted January 10 Share Posted January 10 Yesterday I accidentally left my keys in my Jeep with the ignition on all day. Of course the battery was completely dead (no power at all) But now after jump starting it I’m having this issue where sometimes when I turn the ignition on I have almost no power. Like the battery is dead but it’s not. When the truck does have power and starts, it has really bad idle fluctuation. I worried that leaving the ignition on all day fried something. Could this have damaged the ecu? Also, as a result of this, my head unit no longer functions properly. Half the buttons don’t work Link to comment Share on other sites More sharing options...
eaglescout526 Posted January 10 Share Posted January 10 I would look into the plug for the ignition switch and see. Maybe that’s melted more and causing all sorts of issues. Can’t imagine it damaging an ECU. Just voltage through and through. But I definitely can see it melting that connector and causing no connectivity at a couple terminals. Link to comment Share on other sites More sharing options...
Pete M Posted January 10 Share Posted January 10 weird. have you scuffed/cleaned the contact surfaces at the battery terminals real good? Link to comment Share on other sites More sharing options...
CheepComanche Posted January 10 Author Share Posted January 10 I used this and an excuse to buy the Jeepcables big 7 upgrade. But my battery terminals are clean and tight. I’ll take a look at the ignition switch plug tomorrow morning, but so far I can’t see anything wrong so I'm kind of hoping that the big 7 upgrade will take care of whatever the problem is. I also noticed the lights dimming when the hit the brakes which sounds like a big connection issue somewhere. My main fear is that the problem is something I can’t see like the ecu. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted January 10 Share Posted January 10 The ignition switch plug would be something to look at. If your lights are dimming when you press the brake it could just be a coincidence that your alternator is dying or on its way out. Check voltage on the battery when running. It should be about 14 volts with a properly functioning alternator. Link to comment Share on other sites More sharing options...
CheepComanche Posted January 10 Author Share Posted January 10 Thanks! I’ll be sure to check that too. My alternator is about a year old but that doesn’t mean it’s good. Link to comment Share on other sites More sharing options...
gogmorgo Posted January 11 Share Posted January 11 What did you do to jump start it? If booster cables were hooked up backwards it can do interesting things, blow the diodes out of the alternator, pop fuses… I only know this because I’ve had it happen to me so no judgement if that happened. My first thought was battery terminals. Having a battery go completely dead does sometimes cause corrosion on the terminals. The brown wire at the ignition switch is also a strong possibility. If the blower motor was going, as voltage goes down and a motor slows down, current through a motor goes up, and it will find any weak spot in the circuit. Link to comment Share on other sites More sharing options...
pizzaman09 Posted January 11 Share Posted January 11 Did you actually replace the battery? A battery that was taken down to zero power can easily short out causing all sorts of annoyance on the electrical system. Link to comment Share on other sites More sharing options...
CheepComanche Posted January 12 Author Share Posted January 12 I did get a brand new battery. Just a standard lead acid group 58 from Costco. I used a jump pack to start it and I definitely had the positive and negative correct. Since I’ve had some time to mess with it, I'm pretty sure my problems are coming from the battery terminals. They are clean and tight, but if I move them I can get the truck to do the weird things I talked about originally. It’s weird to me that battery terminals could cause such problems but I believe I have found the issue. Once I’ve got my jeepcables upgrade done, I’ll know for sure! Link to comment Share on other sites More sharing options...
pizzaman09 Posted January 12 Share Posted January 12 The battery cables can be very corroded in the inside. Due to moving them around while swapping out the battery could be breaking down the old cables. Please update us with how the new jeep cables upgrade works out. Link to comment Share on other sites More sharing options...
CheepComanche Posted January 13 Author Share Posted January 13 I got the Jeepcables done. The truck turns over much faster and it hasn’t done anything that I explained earlier. However, there’s been a few things I’ve noticed but haven’t said anything about. The temp gauge is stuck at 120, It will go up but not down. And my isa motor used to click 3 times after shutoff and now it barely works or sometimes doesn’t do anything. Link to comment Share on other sites More sharing options...
eaglescout526 Posted January 13 Share Posted January 13 50 minutes ago, CheepComanche said: The temp gauge is stuck at 120, Does it go down before starting? Does it also move up during cranking but just gets stuck at 120? As for the ISA, I used to hear mine click but after all the cleaning and upgrades I’ve done to the wiring, I haven’t heard mine click in a lonnnnnng time. This isn’t a bad thing, this just means that that the ECU is able to get a better read on where the ISA is after shut down rather than just giving it power until it bleeds off from the ECU. I honestly do not remember the last time I heard mine click. I do hear it move though. It’s quiet since I’ve rebuilt the motor but I do hear it. Link to comment Share on other sites More sharing options...
CheepComanche Posted January 13 Author Share Posted January 13 With the ignition on or the car running It won’t read lower than that. It does move when cranking though. If I unplug the wire from the sender while the cars running, it will drop to 100. But if the car is off and the ignition is on it won’t sit lower than 120. Link to comment Share on other sites More sharing options...
eaglescout526 Posted January 13 Share Posted January 13 I wonder if the connector and the sensor itself are dirty and creating resistance. Link to comment Share on other sites More sharing options...
CheepComanche Posted January 13 Author Share Posted January 13 That’s what I originally thought, but it does the same thing with the sensor unplugged. I will play around with the Jeep some more and see what I can figure out. Sometimes problems go away on their own Link to comment Share on other sites More sharing options...
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