No Electrical Power

[Dammerung]

Just got into my Comanche this morning and turned the key to find out I had no power. As in, it looked like my battery was disconnected - no lights, no fuel pump priming, no click from the starter. I don’t really know what to do at this point. The only thing of note that I could think of is the fact that there’s corrosion on the end of the positive battery cable at the battery and a little at the starter, but that’s it. I replaced the battery cables when I got the Jeep 2 years ago. What is my next step?

 

 

1988 Jeep Comanche Pioneer

4.0 Liter w/ AW4 2WD

[scguy]

First thing, check your battery connections and voltage. Do you have a multimeter?

[Dammerung]

First thing, check your battery connections and voltage. Do you have a multimeter?

Yeah, I checked my battery with my meter and it read out 12.7 volts


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

[jdog]

Headlights work?

If so it's either a bad key switch or a bad fuse link near the battery

[Dammerung]

Headlights work?
If so it's either a bad key switch or a bad fuse link near the battery

Nope, nothing works. No interior or head lights, no starter, no blower, etc etc.


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

[jdog]

Ok,  I'd start with disconnecting the positive side and ohm the wire from the battery terminal to the starter relay

[Minuit]

Any time I work on a vehicle with a sudden, complete loss of electrical power, the first thing I do is take both battery terminals completely off, use one of these on both the cable and battery, and re-connect. I have one of those exact Schumacher battery tools that must be 25 years old now, and it still works great. Buy a handful of them and keep one at home and one in the glove box. There must be no visible corrosion on either the battery or the cable.

 

If the battery terminals are this kind, all bets are off:

In my experience, those are absolutely terrible and you're better off lighting your money on fire unless your OEM terminal literally snapped in half and you're hours from home. I'd rather see a 30 year old OEM terminal than one of those, 99.975% of the time. The best option of all is a military style terminal with side mounted lugs:

 

Following a cleaning of the connections at the battery, look at the starter relay. Everything is connected to the starter relay on a Renix, so those connections need to be clean too. Ditto the grounds. See what I'm getting at here? Make sure every electrical connection in your truck is clean and firmly connected. Bonus points if you apply some type of protectant to prevent future corrosion.

 

[Pete M]

clean those battery terminal mating surfaces.   

[watchamakalit]

 

No power to anything is most likely a battery connection issue of the most basic type.  If it was somewhere else you most likely wouldn't lose everything at once.

[Dammerung]

Took the cable off of the battery terminal and cleaned both sides of the connection until they were shiny. After, my truck interior lights, headlights, etc all came back except my starter. Whenever I would turn the key to try and crank, all power would go. If I put it back into just the on position, power would come back. I think it might be the hot wire to the starter relay, but I’m not sure.
On a related note, could I use the wire that comes attached to the battery cable to jump to the starter relay, or should I run an independent cable with a lower gauge? I think the wire is like 14 gauge, but I’m not sure.




1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

[rokinn]

Your ammeter can read proper voltage and you can still have a dead battery.  Ideally it needs to be load tested but you would have to get it to a load tester.  You can take it out ant take it to a parts store and they can test it for you, I think.  I usually just took mine to my shop.  Check your fluid in the battery to make sure it's up to snuff.  You can put it on a battery charger also and see if it will take a charge and see if that changes the equation.  The fact that you were able to clean up the terminals and get some electron flow back reinforces my opinion on a dead battery.  Easiest place to start imo.  Check to see what the purchase date is on it and how many months of life it's supposed to have.

[Dammerung]

A few days ago my truck decided that it was time for everything to work again after I had cleaned the terminal. I’m still afraid to drive it in case it does leave me stranded, but every time I go out it works. I don’t know what caused the issue while cranking, but it hasn’t come back.


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

[CornFed]

On 12/31/2021 at 6:03 PM, Dammerung said:

A few days ago my truck decided that it was time for everything to work again after I had cleaned the terminal. I’m still afraid to drive it in case it does leave me stranded, but every time I go out it works. I don’t know what caused the issue while cranking, but it hasn’t come back.


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

Was it particularly colder when it didn't want to start, than it is now that it will start?

[Dammerung]

Was it particularly colder when it didn't want to start, than it is now that it will start?

It’s been cold around here at 50 degrees, and it was around 45, may be 40 degrees that time, but I don’t think that was enough to cause the issue but I’m not sure


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

[CornFed]

4 hours ago, Dammerung said:

It’s been cold around here at 50 degrees, and it was around 45, may be 40 degrees that time, but I don’t think that was enough to cause the issue but I’m not sure


1988 Jeep Comanche Pioneer
4.0 Liter w/ AW4 2WD

I had just put a new battery in mine a few months back. Turn around and it wouldn't start the first cold day we had but when it was warm out it was fine. Never even hesitated. Put a new battery in again and it fires up fine in the cold. May not be your problem just trying to trouble shoot.