Trouble Code 41 + voltage gauge fluctuation help - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > Trouble Code 41 + voltage gauge fluctuation help

Stainless Steel Door Hinge PinsPoly Door Hinge BushingsDisc Brake Kits from ECGS

Reply
Unread 01-15-2012, 12:16 PM   #1
tkwok
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2006
Location: california
Posts: 85
Trouble Code 41 + voltage gauge fluctuation help

I got a trouble code 41 (Alternator field) a couple of days ago when I started up my YJ on a cold morning. I put a multimeter on the battery terminals on while the jeep was running today and I got a ~14.6v reading. So I took the jeep for a short drive today and noticed the reading on the voltage meter was just a little above the quarter tick mark. I've never noticed the gauge running below the 14v mark while the jeep was running before. But a little later during the drive, the gauge needle went back up to the "normal" reading at a little above the 14v tick.

Can anyone tell me what else I should be checking to diagnose this problem? Do I just have a bad battery on its way out?

thanks

tkwok is offline   Reply With Quote
Unread 01-15-2012, 12:43 PM   #2
SDGBASSE
Registered User
1990 YJ Wrangler 
 
Join Date: Jul 2009
Location: Mtl, Qc
Posts: 650
Bad battery, loose connection, bad ground, bad voltage regulator, loose belt any of these could be your culprit. Try wiggling around the wires while someone watches the gauge and look for a drop then you can go to a parts store and get your battery and alternator checked out for free.
__________________
[QUOTE=ZeroGravity;10681914]I didn't click the link because it says "power probe" in the url.[/QUOTE]
SDGBASSE is offline   Reply With Quote
Unread 01-16-2012, 08:04 PM   #3
tkwok
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2006
Location: california
Posts: 85
Replaced the battery today because it tested bad at autozone. Hooked the new battery to the jeep and code 41 still shows up. How do i test the voltage regulator and for bad ground?
tkwok is offline   Reply With Quote
Unread 01-16-2012, 09:18 PM   #4
SDGBASSE
Registered User
1990 YJ Wrangler 
 
Join Date: Jul 2009
Location: Mtl, Qc
Posts: 650
The voltage regulator should have been tested with the charging system ( its internal to the alternator on YJs) and the battery if they plugged the tool to the vehicle, if that's how they did it then it's probably good. As for the grounds, you'll need to clean them up good if they got corrosion on them, that's about it. How long was the battery unplugged for when you replaced it? The ECU an take a while to clear its memory, also do you still have a voltage issue or is it just the code?
__________________
[QUOTE=ZeroGravity;10681914]I didn't click the link because it says "power probe" in the url.[/QUOTE]
SDGBASSE is offline   Reply With Quote
Unread 01-16-2012, 09:30 PM   #5
rebelone50
Registered User
1991 YJ Wrangler 
 
Join Date: Jul 2008
Location: Texas
Posts: 171
on 91 and later did the regulator move from the alternator to the computer? Are later YJ's alternators minus an internal voltage regulator?
__________________
"the Lord God has special providence for fools, drunkards, and the United States of America."--Otto Von Bismarck

“We sleep safely in our beds because rough men stand ready in the night to visit violence on those who would do us harm.” – Winston Churchill
rebelone50 is offline   Reply With Quote
Unread 01-16-2012, 10:17 PM   #6
tkwok
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2006
Location: california
Posts: 85
The battery was disconnected for more than 1 hour. I even touched the positive and negative terminals together afterwards to clean the trouble codes. I only tested the battery at autozone, not the alternator. I thought from reading on JF, the voltage regulator was located at the PCM on a '95 YJ? Can someone here confirm that?

One more thing I noticed tonight after installing the new battery was my headlight seemed dimmer than usual. Voltage read above 14v on the gauge inside the Jeep. When I hit the gas pedal a little, the light would get brighter and when I let off the gas, it would go dim again. I was hesitant to drive the Jeep around the streets fearing that it might die on me tonight so I didn't get a chance to check out the voltage fluctuation. Can someone tell me how many different grounding points are on a YJ? I want to check them next. At this point, i'm thinking the alternator is about to go out on me.
tkwok is offline   Reply With Quote
Unread 01-16-2012, 11:12 PM   #7
SDGBASSE
Registered User
1990 YJ Wrangler 
 
Join Date: Jul 2009
Location: Mtl, Qc
Posts: 650
They differ from years and trims, the most common ones are on the right side of the engine on the oil stick, the left side of the engine in the back on a head bolt stud, under the dash next to the parking brake pedal and I think I'm missing one.

I'm not a 100% positive about the voltage regulator being moved out of the alternator or not, but if you're still getting the code and your headlights are fluctuating with RPMs, it looks like a charging issue and not a battery one. Before you spend more money make sure the belt is tight enough and isn't slipping on the alternator pulley.
__________________
[QUOTE=ZeroGravity;10681914]I didn't click the link because it says "power probe" in the url.[/QUOTE]
SDGBASSE is offline   Reply With Quote
Unread 01-17-2012, 07:49 AM   #8
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,571
91-95 the ECU regualtes the charging. The faults should clear when you disconnected the battery. The voltage at the battery may be ok but the connection at the PDC is really where you need to check the power. I would go through and clean all the wring from the alternator to the battery and the battery to the PDC. That includes the grounds to the body and engine. Check the 2 big 50 amp fuses in the PDC (fuse block). Get the alternator tested.
Que89YJ is offline   Reply With Quote
Unread 01-17-2012, 08:02 AM   #9
PFCLinscomb
Registered User
1994 YJ Wrangler 
 
Join Date: May 2011
Location: Lafayette, LA
Posts: 120
You alternator is about to die. 5 Bucks says it is.
__________________
Times you kick yourself in your own ***: When that stupid Private wakes the whole platoon up by running through the bay screaming "Reveille,Reveille,Reveille!!!!!!!!!!!!!!!!!!!!" And your like "Who the hell put that guy on last fire guard" and then you realize.... You did -.-
PFCLinscomb is offline   Reply With Quote
Unread 01-24-2012, 05:43 PM   #10
tkwok
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2006
Location: california
Posts: 85
took off all the connections to the alternator this past weekend and cleaned all the contact points. I connected everything up and fired up the Jeep. I hooked my multimeter up to the positive lead of the alternator and ran the negative to a ground on the Jeep. I was getting a +14.7v reading. I turned some accessories on and rev'ed the engine up to 2000RPM and looked at the reading again. It was at a steady +14.7v. The headlights are also no longer dimming randomly the engine is off. Hopefully, cleaning the connections fixed my problem.
tkwok is offline   Reply With Quote
Unread 01-24-2012, 07:32 PM   #11
SDGBASSE
Registered User
1990 YJ Wrangler 
 
Join Date: Jul 2009
Location: Mtl, Qc
Posts: 650
How about the code, still getting that or did it go away?
__________________
[QUOTE=ZeroGravity;10681914]I didn't click the link because it says "power probe" in the url.[/QUOTE]
SDGBASSE is offline   Reply With Quote
Unread 01-25-2012, 01:24 AM   #12
tkwok
Registered User
1995 YJ Wrangler 
 
Join Date: Aug 2006
Location: california
Posts: 85
The check engine light (code) went away as well.
tkwok is offline   Reply With Quote
Reply

Tags
alternator , battery , voltage drop
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.