Voltage fluctuations

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

Checked dtc with Innovate code reader and found:
P0403 egr open
P0102 maf low input
P1140 egr throttle circuit open
All these make sense because the egr delete kit is installed and the mag is unplugged. Took Liberty to Autozone to use code reader and found:
P1140 vacuum reservoir solenoid open or short to ground
3EFE abs
6EFE battery pack voltage out of range
6FFE body controller module missing
19FE wheel speed lf input signal missing
21FE wheel speed rf input signal missing
When driving the warning chime activates then the gauges, instrument lights and fan go off for a second or two and come back on. The problem seems to start after the Liberty warms up. It affects the engine also. Looking at the fsm it looks like the body control module is on the right hand side of the firewall. I had to replace the tcm about 400 miles ago. This started after the transmission was rebuilt about 150 miles ago. I’m going to check the connections. What else can I look for?

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

Ok, read the fsm section 8 body control module and it controls a lot of body operations but nothing engine related from what I can see. My question is the body control module specific to the Liberty CRD?

WWDiesel · **Posted:** Sat Apr 17, 2021 11:14 pm

daytona701 wrote:

Ok, read the fsm section 8 body control module and it controls a lot of body operations but nothing engine related from what I can see. My question is the body control module specific to the Liberty CRD?

I checked several of the Mopar Web sites and yes, it is unique only to the 2005 model Liberty.
But the good news, it was used on the 2005 2.4 & 3.7 gassers as well, so the bone yards should have some.

Body Control Module (BCM) -- 5142220AC
From the one of the Mopar sites:
VEHICLE FITMENT
Make Body & Trim Engine & Transmission
2005 Jeep Liberty Limited, Renegade, Sport 2.4L L4 - Gas, 2.8L L4 - Diesel, 3.7L V6 - Gas

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

Thanks WWDiesel, I’ll poke around today checking the grounds and maybe adding one or more. That may fix it. Trying to get the Liberty dependable but it’s putting up a fight.

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

2005 Jeep Liberty factory service manual section on Body Control Module has a ground wire that includes 5 JB/BCM associated ground circuits with eyelet terminal end on a stud secured with a nut next to the JB/BCM. The JB (junction block) is the fuse panel facing the drivers door at the drivers side instrument end panel with the snap on cover. The Body Control Module is attached to the side of the JB. The ground connection precise location is drivers side instrument panel end bracket near the JB/BCM.
The nut on the stud was slightly more than finger tight. After tightening about half a turn test drove about 20 miles and flickering instrument panel stopped. Still have fluctuating fan speed from ac. Clean tight ground are a good thing with all circuits.

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

I had often checked battery voltage at rest (12.5) and running (14.4). I didn’t check when voltage problems first appeared assuming it was ok and I should have checked. Turns out alternator failed and caused battery voltage drop while engine was running. This caused all the icons popping up on the dash and dtc codes. A simple voltage check when the problems first appeared would have indicated a problem with the charging circuit. I did unplug the front control module (specific to 2005 Liberty CRD) and cleaned the contacts and plug. From my understanding the bcm may control alternator output voltage. I also ran a ground wire from the bcm case to the ground behind the driver side headlight. I had previously ran a ground from the battery negative to the ground behind the drivers side headlight. I also used a longer bolt because after stacking the ground eyelets the existing bolt was too short. With the low stall torque converter, rebuilt transmission, in tank pump, new fuel head, 2 micron filter, new alternator and cleaned and tightened grounds the Liberty is starting, idling and running better than ever. Next is heavy duty cooling upgrade, rebuild both drive shafts, tires and then tuning the engine and maybe the transmission. I couldn’t have done it without this forum and those that contribute. Thanks so much.

Billybob · **Posted:** Sat Apr 24, 2021 1:14 pm

When I have suspect voltage issues I plug my Multimeter into the front Power Outlet so I can monitor the voltage while driving.

For instance I had a weird problem whereby if I activated the front Wipers I could see the voltage steadily rising. When it hit +17 Volts the the Cluster would "Ping" and the engine would cut out.....would restart after a few seconds.

Turned out to be one of my many wiring issues whereby one of the Wiper Motor wires was shorting somewhere to some other random wire.

Unfortunately I had a long drive to get back home and it was raining extremely hard....by the time I got home the Lead Acid Battery had boiled itself to death! :cry:

Voltage fluctuations

Who is online