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It's not a dead battery, what is it?

racerized

NAXJA Forum User
Location
Windsor, CO
1990 Jeep Cherokee, 4.0 I6, AW4

This past week I noticed my startups (cranks) were beginning to slow down. The jeep runs just fine once it's started, aside from the Renix high idle plague I'm still trying to fix. But today, it almost didn't startup while I was running errands, so I decided to go straight home because I was afraid I wouldn't be able to get it started again. Good thing I did, cause sure enough, now it won't start. My battery test good 11.8V while cranking, but it SOUNDS like my battery is dying. My brother says it sounds like the motor is starting to cease... Can anyone help me? I know these year Jeeps are quite finicky, so I'm hoping it a quick fix... Although with my luck so far with this Jeep I'm expecting the worst.

Chris
 
how are your cables? if they are major corroded they won't let full voltage get anywhere.
 
11.8 v cranking seems pretty good...what about voltage with no load? I agree with other posts...check connections GOOD. Then see what happens
 
Check the starting voltage at the starter!
 
After the Jeep has sat for several hours the voltage at the battery should be 12.5-13.0.
With the engine running the voltage should be 13.3-14.5.
Slow cranking can be caused by bad connections (as others have posted), corrosion inside cables and dirty starter brushes....
 
11.8 v cranking seems pretty good...what about voltage with no load? I agree with other posts...check connections GOOD. Then see what happens

Are you sure about that? 11.8V seems low enough to cause a slow crank to me.

My voltage doesn't change at all while cranking... but then again I have two deep cycle 31's so my opinion on this may not be relevant.

My guess is a bad battery, but you can figure that out for sure pretty quick by taking it to a shop and having them test it.
 
1990 Jeep Cherokee, 4.0 I6, AW4

This past week I noticed my startups (cranks) were beginning to slow down. The jeep runs just fine once it's started, aside from the Renix high idle plague I'm still trying to fix. But today, it almost didn't startup while I was running errands, so I decided to go straight home because I was afraid I wouldn't be able to get it started again. Good thing I did, cause sure enough, now it won't start. My battery test good 11.8V while cranking, but it SOUNDS like my battery is dying. My brother says it sounds like the motor is starting to cease... Can anyone help me? I know these year Jeeps are quite finicky, so I'm hoping it a quick fix... Although with my luck so far with this Jeep I'm expecting the worst.

Chris

when it does that open the hood and tap and or wiggle the two center most relays in the strip of 4 relays on the passenger side. One of them is the +B latch relay and can cause a high idle issue if bad and or corroded..

Take the battery out and have it tested. 11.8V cranking is low in my book. The volts may be OK, BUT the cranking amps might not be enough(weak battery). Most if not all parts stores can check it these days, but the battery has to have a good charge on it to test it.

They are not that bad after you take them out and wine and dine them a few times... Well both my 89's are not bad atleast...lol

and as stated a few times I see.....make sure all the connections are clean and I'm not talking just the outside...take them off and clean the contact area of the positive and ALL the grounds.
 
A bad ground will kill a starter if I remember correctly. I replaced all grounds a short while after replacing a starter just as a precaution. At the time they were 15 years old if they were original. I bought the car at 150K on the odometer. So I doubt that they were new judging from their appearance.
 
11.8 v cranking seems pretty good...what about voltage with no load? I agree with other posts...check connections GOOD. Then see what happens

Did anyone mention Alternator? Could cause the weak battery symptoms. Take it AutoZone, they'll test both still in the Jeep, and point to your culprit.

11.8 is a fail on the alternator test. If the batt is only putting out 11.8 your Jeep won't start (neither will my Nissan).

I had the same prob with my Nissan...replaced alternator...again...on warranty. Problem gone.

:patriot:
 
Are you sure about that? 11.8V seems low enough to cause a slow crank to me.

My voltage doesn't change at all while cranking... but then again I have two deep cycle 31's so my opinion on this may not be relevant.

My guess is a bad battery, but you can figure that out for sure pretty quick by taking it to a shop and having them test it.


With everything working properly, stock OEM, it is not unusual for the cranking voltage to drop as low as 10 volts on an old battery. The minimum should be about 10 volts. IIRC mine cranked just fine with all clean cables and a brand new HD battery at about 10.7-11.0 volts minimum, tested at the battery with a multi meter.

I suspect the grounds are bad, or there is a bad connection between the battery and the starter (or both), as he has too much voltage for a slow crank. A slow bogged down crank should have a voltage under 10 volts, due to the excess load, bad battery or both. He is assuming the battery is OK, which I think is premature based on what little tests he posted so far. Also batteries are notorious for acting good, and then dying a sudden death, with little warning.

I am also wondering where and how he tested the battery voltage during cranking? It needs to be tested at the battery posts!!!
 
Did anyone mention Alternator? Could cause the weak battery symptoms. Take it AutoZone, they'll test both still in the Jeep, and point to your culprit.

11.8 is a fail on the alternator test. If the batt is only putting out 11.8 your Jeep won't start (neither will my Nissan).

I had the same prob with my Nissan...replaced alternator...again...on warranty. Problem gone.

:patriot:

He said the cranking voltage was 11.8 V (not the unloaded voltage or the running with the alternator on voltage), which is actually way high when the starter is cranking for an OEM setup. 10.0 cranking volts is the minimum on a Renix Jeep.


The battery should have about 12.75 volts when the jeep is off, not under load. And as stated before, 13.25 to 14.5 volts is normal under varying load conditions, engine running. All read between the battery posts. The dash gauge on Renix is useless for getting exact voltages on the system or battery.
 
With that voltage while cranking, I would not suspect a bad battery. Decreasing cranking speed over time would steer me towrds corroding connections in the + path and/or the ground path. Ground path is just as important as the + path.

Also I would suspect the starter. Perhaps the armature bushings are going bad. That would cause significant drag in the starter.
 
I checked and cleaned the connections to the starter motor, solenoid and relay, whacked it with a hammer 3 times and it started right up. Safe to say I need a starter. Thanks for all your comments. You guys sure are helpful.
 
I checked and cleaned the connections to the starter motor, solenoid and relay, whacked it with a hammer 3 times and it started right up. Safe to say I need a starter. Thanks for all your comments. You guys sure are helpful.

It may just need a new starter solenoid on the top, if whacking it worked to get it to start right up.
 
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