Starting/Electrical issues

[Rmartinson]

I’m having issues starting my 2018 Wrangler JL. When I go to start it everything comes on as normal but when I push the start button it clicks 1 time and does not activate the starter. I had this issue 11 months ago. I replaced both batteries at that time but that did not help. A local shop found the starter to be bad and after replacing that it worked fine for the past 11 months. Now the same issue is back. I can get it to start by jumping or charging the batteries. But a day or so latter the issue is back. The vehicle did sit for about a month recently while the shop repainted hinge corrosion. So I’m sure it never was running during that time. It took about a week of driving for the stop/start to return to working after that time. I’ve been watching the dash volt meter while driving. Under normal driving at a constant speed it is around 12.4-12.5 volts. When I slow down to stop it jumps up sometimes as high as 14.4 and drops down again in the 12.5 range when stopped. Had both batteries tested. Both are only 11 months old. Large battery came back good testing from both battery posts. Small battery we tested from the negative large battery post and the positive small battery post under the fuse cover. (Think it’s called F1). That battery came up possibly bad. (The stop start is working) The alternator also came up with a possible voltage regulator issue. (Had the tests run at a local parts store)
Wondering what people’s thoughts are on where to begin replacing things. Sorry for the long post just wanted to try to list all the facts/issues. Thanks so much for any help or insight you may have.

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[Heimkehr]

I’ve been watching the dash volt meter while driving. Under normal driving at a constant speed it is around 12.4-12.5 volts. When I slow down to stop it jumps up sometimes as high as 14.4 and drops down again in the 12.5 range when stopped.

The alternator also came up with a possible voltage regulator issue.

The undercharging whilst moving -- 12.5 volts -- is a charging system red flag. It should be 13.9 to 14.2V. The voltage regulator may indeed be an issue here. Possibly a deeper dive into the alternator is warranted. It may be adversely affecting the service life of the still-young batteries. Know also that one bad battery will eventually hurt the other one.

 

[Yawnie'sPapa]

The undercharging whilst moving -- 12.5 volts -- is a charging system red flag. It should be 13.9 to 14.2V. The voltage regulator may indeed be an issue here.

There is no voltage regulator. It's controlled by the PCM based on information from the IBS, engine torque required, going up hill, down hill, ambient temperature and other factors.
The normal range is from about 12.6 to 15.0 and that can fluctuate.
If the battery is at a 100% state of charge and/or running hot, the PCM cuts the alternator back and the voltage will drop because the vehicle is then running mostly from the battery. If a large increase in engine torque is required at the same time, the alternator is totally cut off.
The exact voltage you see can be 14.7, for example, if you haven't driven the Jeep for a while and the batteries are down. I 've seen mid to low 13s if the batteries are full, it's a warm day and I'm going up any of the many hills around where I live. Then when I crest the hill and start to coast down, the voltage will climb above 14.
There's no rule saying what it will be for my Jeep compared to your Jeep - too many variables.
If the alternator is fine and if all electrical connections are first checked and found to be ok, then yoj may be looking at an IBS or PCM issue.
Any time batteries are replaced- ALWAYS:
Charge each battery fully before installing
and
Leave the IBS disconnected for at least 15-20 seconds to reset it so it will learn with new batteries.
Skipping either step can lead to really weird things like weird voltages, batteries not staying up and so on.
I resolved issues by separately charging both batteries with a good AGM charger (10 amps or more) and let it go through all charging phases, and leaving the IBS disconnected from everything for a while to reset it. Charging voltages and weirdness went away.

Yes, the brake regen applies to gas and diesel Jeeps - it's when the system senses you are braking, need no extra engine torque, and it ups the load on the alternator to regenerate the 12v batteries.

Oh, and parts stores don't know how to properly check batteries and normally don't know squat about today's smart alternators (well, it's really a smart charging system, the alternator itself has no smarts - it's just a modern version of your 1975 Plymouth alternator) A parts store is the last place I want messing with the charging system on my Jeeps and I don't trust their battery tests because they just don't do the whole slate of tests properly with those hand-held devices, especially when trying to test a battery that isn't fully charged. You get bogus results.

 

[Rmartinson]

Thanks for the great information. Not to sound ignorant but can you tell me what IBS and PCM stand for.?
Also I was thinking of recharging each battery and reseting the IBS as you mentioned (disconnecting it) Could you explain further how this is done. Again sorry for my lack of knowledge.

 

[GATORB8]

Thanks for the great information. Not to sound ignorant but can you tell me what IBS and PCM stand for.?
Also I was thinking of recharging each battery and reseting the IBS as you mentioned (disconnecting it) Could you explain further how this is done. Again sorry for my lack of knowledge.

IBS = Intelligent Battery Sensor
PCM= powertrain Control module.

 

[Rmartinson]

Great Thanks for that information. I did find a fuse for each of those. If I pull the fuse for the IBS am I correct that it will reset that info about the batteries? (After I make sure both are fully charged) Thanks again for all the info.

 

[Rmartinson]

Ok after doing a little more research I did find the IBS module on the negative terminal of the large battery. I am in the process of making sure each battery is fully charged and will then unplug the IBS at the battery for a short time to hopefully reset it. I will keep you posted as to the results.

 

[Leisure Freak]

I had the same thing. First time all looked normal as I entered the JL, pushed the start button, and the whole thing went dark, zero power. I opened the door to go out to lift the hood and everything immediately came back on. It then started as normal. Then about every other start all I got was the relay click/no starter engagement and then normal start on the second attempt. I finally got tired of that and decided to check connections and with a little effort I could twist the positive battery cable. I tightened it down and it has been perfect ever since. Battery cable was tight but not tight enough. I had replaced the main battery about 2500 miles before my first no start event. A washboard road drive probably did my inadequate connection in. These JLs are very power finicky.

 

[Rmartinson]

Thanks. I will check mine. Appreciate it.

 

[Rmartinson]

So here is an update on my on going issue. After charging both batteries fully and then unplugging the IBS for a short time and replugging it back in everything worked fine. After 3-4 days the issue came back. I decided to pull both batteries and have them tested outside the vehicle. Both batteries tested good. I put them back into the vehicle and made sure all connections and clamps were tight. It started just fine. Everything seems to be working fine and the stop/start is working fine as well. Again after a few days of starting fine the issue is back. When I jump start it it takes very little effort for it to start. Can I unplug the IBS? If I do that and drive it would that possibly rule out a bad IBS if the issue doesn’t return? Thanks for any ideas.

 

[Heimkehr]

I decided to pull both batteries and have them tested outside the vehicle. Both batteries tested good.

Thanks for any ideas.

Did you monitor the battery's voltage with it in situ, during a starting event?

Batteries can pass a bench test (as you've done) with acceptable voltage. The voltage can then fall off of a cliff when cranking the engine, no matter how brief that demand may be.

This is just one more thing to attend to, in order to determine a Pass/Fail for that particular metric. ?

 

[jhackathorne]

OP... your situation is almost identical to mine. Both batteries are new and they are trying to figure out the next step. I talked to @Rhinebeck01 and he gave some advice as well. I asked dealer to check the green Can Bus next as I have replaced the Z Fuse Array so that is eliminated. So that is something you may want to have looked at. Good luck!

 

[18BlackJLRU]

I’m having issues starting my 2018 Wrangler JL. When I go to start it everything comes on as normal but when I push the start button it clicks 1 time and does not activate the starter.

I just had the same issue… The batteries tested good… they suspected the stater…. when they disconnected the stater cable, they noticed that the connector was corroded…. They cleaned it and it’s all Ok !

 

[Rmartinson]

So here is the latest update on my starting issue. I unplugged the IBS and drove it for about 5 days. Of course the stop/start warning light was illuminated on the dash. I had no starting issues while the IBS was unplugged. So I decided to replace the IBS. After replacing the IBS the stop/start warning light went away and I have had no starting issues. This seems to have fixed my issue. Thanks to all that commented and gave great feedback for my issue. Hopefully this might help others if this issue comes up.

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