First repair on Jeep

Status
Not open for further replies.

OVERKILL

$100 Site Donor 2021
Joined
Apr 28, 2008
Messages
57,913
Location
Ontario, Canada
Still under warranty, dealer had it for most of last week. I was in Michigan until today, so didn't get it back until about an hour ago.

Problem:
For the last few weeks the interior light dimming looked like Michael J. Fox was operating a dimmer switch. Instead of progressively fading out, it was jazzercised. This only happened when the vehicle was running. Shortly after this was observed the FCW/ACC system began to freak out indicating that it was impaired. Then the cluster rebooted. Then it rebooted again, several times. Got to my destination, it was fine when I went to leave. This happened again. I assumed we were having some sort of voltage issue and a quick Google seemed to indicate that a bad/weak battery has been the cause of this on other JGC's. I thought voltage regulator or alternator, given that the battery seemed fine. Regulator is internal to the PCM.

I checked the battery cables, I could, with some effort, rotate the negative, so I tightened it down, no difference.

At this juncture I decided to start watching the voltage gauge on the SRT Performance Pages app and woweeee!!! She was flip-flopping from 11-17V at one point; it was all over the map.

Took it into the dealer, they originally suspected a bad ground, however after checking all of them, they ruled that out. Bench tested the alternator, which came back fine (battery also tested fine, it has a large AGM) but decided to put one on before looking at replacing the PCM.

New alternator appears to have resolved the issue. Voltage is a steady 14.4-14.7V now, interior lights are normal...etc.

It has ~36,000Km on it at this point.
 
Good to hear you got it resolved, a new alternator and battery, covered under warranty is not too bad all things considered.

Also, it's great the vehicle is equipped with all these gauges, so that you could see the problem live. With modern infotainment system and these huge screens, it's a shame manufacturers don't include this type of info in non performance models.
 
Originally Posted by KrisZ
Good to hear you got it resolved, a new alternator and battery, covered under warranty is not too bad all things considered.

Also, it's great the vehicle is equipped with all these gauges, so that you could see the problem live. With modern infotainment system and these huge screens, it's a shame manufacturers don't include this type of info in non performance models.


They didn't end up replacing the battery, since it seemed to be OK. Since it only happened when it was running, alt was what they went with.
 
Originally Posted by OVERKILL
it has a large AGM

Interesting it has AGM battery. I'm pretty sure a traditional flooded lead acid one sits in my Charger.
 
Originally Posted by KrisZ
Oh, I thought since both tested OK they changed both. Thanks for clarifying.


No problem. They only wanted to change one part, and the one that was the most suspect in this case, based on what was being observed after a bad ground was ruled out.
 
Originally Posted by Quattro Pete
Originally Posted by OVERKILL
it has a large AGM

Interesting it has AGM battery. I'm pretty sure a traditional flooded lead acid one sits in my Charger.


Yeah, the battery looks almost identical to the one that was in my M5 actually. It's quite large and is situated under the passenger seat with the two handles that meet in the middle coming off of it. Says AGM right on it.
 
Originally Posted by KrisZ
Weird that the alternator bench tested fine with such a wide voltage variance observed when it was in the car. I wonder what that bench test, exactly tests.


I'd wager just current output, since there's no regulator to test, given it is in the PCM. Really goofy failure though, and definitely infant mortality given the age and mileage. Hoping the new unit is a star performer, lol
wink.gif
 
Sounds like it's a good thing you (a good mechanic) was the owner and not a regular customer-that sounds like it could have been fun to diagnose (if it did it intermittently).
 
Originally Posted by bullwinkle
Sounds like it's a good thing you (a good mechanic) was the owner and not a regular customer-that sounds like it could have been fun to diagnose (if it did it intermittently).


thumbsup2.gif
I could see this being fun to troubleshoot, lol.
 
Originally Posted by KrisZ
Weird that the alternator bench tested fine with such a wide voltage variance observed when it was in the car. I wonder what that bench test, exactly tests.


I bet there is a PCM control going on. A lot of the newer Fords have them and you are "supposed" to use the IDS to tell the computer there is a new battery when you change it so it knows to charge accordingly. Thankfully it isn't as drastic as BMW where you have to register the battery.

O and the warranty people hate it when techs pull out the parts cannon/wheel of parts instead of spending time doing proper diag.
 
There's a HUGE issue involving the alternators in those vehicles, although FCA did their best to avoid fixing it.

I constantly have GC's and Durango's come in the shop with all kinds of weird electrical issues, and it's ALWAYS the alternator.

There's huge threads on the forums about these, it's mostly the 3.6 engines but there have been reports of the V8's going bad as well. You're lucky, many people have reported TIPM and PCM failures due to the spikes in AC voltage introduced to the system from failed diodes.
 
Originally Posted by 14Accent
There's a HUGE issue involving the alternators in those vehicles, although FCA did their best to avoid fixing it.

I constantly have GC's and Durango's come in the shop with all kinds of weird electrical issues, and it's ALWAYS the alternator.

There's huge threads on the forums about these, it's mostly the 3.6 engines but there have been reports of the V8's going bad as well. You're lucky, many people have reported TIPM and PCM failures due to the spikes in AC voltage introduced to the system from failed diodes.


I'd wager it was due to me catching it early, which was in part caused by the FCW/ACC feature acting up and the track-down that resulted. Everything else was working fine, so I could easily see somebody with a vehicle without that system driving it until it got much, MUCH worse, causing severe damage.
 
Hopefully the big scary looking alternator/motor unit on the new E-torq equipped hemis and pentastars is a good one. I'd hate to see the price tag on one of those.

We never had an issue with our 2013 Grand Caravan in the 70K miles we owned it, but it would kind of flicker the headlights a bit at times. The pentastar in my 2017 Ram 1500 does that as well depending on electrical load.
 
Last edited:
Originally Posted by 14Accent
There's a HUGE issue involving the alternators in those vehicles, although FCA did their best to avoid fixing it.

I constantly have GC's and Durango's come in the shop with all kinds of weird electrical issues, and it's ALWAYS the alternator.

There's huge threads on the forums about these, it's mostly the 3.6 engines but there have been reports of the V8's going bad as well. You're lucky, many people have reported TIPM and PCM failures due to the spikes in AC voltage introduced to the system from failed diodes.


good info.
any idea how long fca has been getting bad alternators? and, who is the vendor ? tia.
 
Originally Posted by bdcardinal
Thankfully it isn't as drastic as BMW where you have to register the battery.


With my Carly app it takes all of three minutes to register the battery.
 
Originally Posted by yeti
Originally Posted by 14Accent
There's a HUGE issue involving the alternators in those vehicles, although FCA did their best to avoid fixing it.

I constantly have GC's and Durango's come in the shop with all kinds of weird electrical issues, and it's ALWAYS the alternator.

There's huge threads on the forums about these, it's mostly the 3.6 engines but there have been reports of the V8's going bad as well. You're lucky, many people have reported TIPM and PCM failures due to the spikes in AC voltage introduced to the system from failed diodes.


good info.
any idea how long fca has been getting bad alternators? and, who is the vendor ? tia.


I'm interested as well. I've yet to see my dealer swap an alt on a GC or Durango, so I'd expect I would have if this issue was as widespread as stated
21.gif


Looks like the part #4801834AB for the unit is spec'd for 2014-2018, though aftermarket applies it more broadly to include 2012-2018...


Regarding who makes it, it looks like it might be a Denso unit, based on this pic? The Honda OEM ones look very similar.
[Linked Image]
 
Originally Posted by Quattro Pete
Originally Posted by OVERKILL
it has a large AGM

Interesting it has AGM battery. I'm pretty sure a traditional flooded lead acid one sits in my Charger.

It's under the front passenger seat too! Well, at least the 3.6L models.
 
Originally Posted by Nick1994
Originally Posted by Quattro Pete
Originally Posted by OVERKILL
it has a large AGM

Interesting it has AGM battery. I'm pretty sure a traditional flooded lead acid one sits in my Charger.

It's under the front passenger seat too! Well, at least the 3.6L models.


Yup, same spot.
 
Status
Not open for further replies.
Back
Top