2002 LB7 Voltage Issues

[DirtyMax9812]

Hello! I have a 2002 LB7 that has been having some voltage issues as of late.
I always turn the key to the run position to let the glow plugs warm, no matter what time of year. As soon as the "Wait to Start" light goes out I start it. When I start it, the voltage remains at about 10 or so volts for about 30-45 seconds after the truck has been running, then all of a sudden it will jump to the normal 14 volt reading. I just replaced both batteries today, so that is not the problem. This has been going on for about a year now. The part that is starting to worry me now, is that the past week or so, every time I start the truck the clock has been reset to 1:00. I cant seem to find a standard answer to what is actually going on. The guy at AutoZone says it may be a "Sticky Glow Plug Relay" Different Diesel Forums online say it could be the glowplug heater realy is bad, others say it could be the Air Intake Heater, and other forms say that it's normal, and its showing that the alternator is working correctly. All i know is that its irritating that I have to set the clock in my truck every day, and all the lights, and heater are very weak for the first 30-45 seconds, before coming up to normal speed. Any help is much appreciated!

 

[AKlowriderZ71]

What you are noticing (except for the clock) is normal. Your air intake heater stays on for that long on cold engine startups, and your volt gauge will read that low until it turns off.

Some guys remove the air intake heater, but that might not be an option depending on where you live. Here in Wyoming, it's a good thing to have working when it's -20F. If removed, I think you need to change your tune.

Clock setting to 1:00 on engine starts is usually a loose battery cable end.

 

[DirtyMax9812]

Thanks for the reply!

But the strange thing is, its only been happening for about the last year, with the voltage thing. The clock, about the last week. Im in Michigan, so I know all about the cold. But it does it when its 90 out too. I know the battery cables are tight too, because I just put in 2 new ones today.

 

[AKlowriderZ71]

The intake heater comes on with every cold engine start, even when it's 90 degrees outside. You are experiencing a normal condition that you didn't notice previously. Trust me, unless you delete it, you are chasing your tail. Save your time & money, it's normal.

 

[DirtyMax9812]

:thumb: good enough! That's all I needed to hear . Thanks for the advice

 

[TheBac]

Been cold this week, hasn't it? Guess winter decided to show up after all.

For the hell of it, check your ground leads attached to the inside of the cab mount just under the driver's door. Clean them good. That might help.

 

[DirtyMax9812]

ok, all the mounts are good, and grounds seem to be ok... where do I go from here? Every time I shut the truck off and start it back up, the clock is reset to 1:00. All the radio presets are still there. What is causing it to reset every time it's started?

 

[Porno Joe]

does the entire radio reset- ie all the presets are gone too -or is it solely the clock?

everything else you described is normal except for the radio. would almost make me wonder if something in the radio isn't bad

 

[DirtyMax9812]

it's only the clock, and it's only been doing it for about a week now. all the presets remain. I can leave the radio on, and turn the truck off at 6pm, and immediately restart it, and the radio will be off, and at 1:00.

 

[Porno Joe]

that sounds like a radio problem to me

 

[Dmax87]

Yeah I agree on the radio having an issue. If you had low voltage or a dead battery you should lose everything on your radio like presets and clock. The voltage reading is normal glow plugs and intake heater draw a lot of current. I had a glow plug relay stick on my truck from a wrench shorting to ground on the glow plug relay block while I was doin injectors. It blew the main fuse Then the relay stuck about a week after and literally killed both batteries in about 3hrs.

 

[kevincolyar]

Having this same issue. Batteries and alternator checked out okay, replaced battery terminal bolts and cleaned connections, cleaned ground under driver side door.

One thing I do have to add is that my clock seams to reset at the instant my Edge CTS3 starts reading gauges, as if the CTS is pulling just enough current to make the radio reset. This is only when the truck is cold.

 

[TheBac]

These trucks are very susecptible to strange electrical goings-on under low voltage on start up and cold start/low voltage scenarios. Did you load test the batteries individually?

 

[kevincolyar]

Just had them load tested individually; tested great. Both are one year old AC Delcos.

 

[mojito5000]

I finally took out my Edge because of all the weird issues it caused on the truck. It’s a fun product, but it causes issues. Do you have the juice too, or it’s the CTS?
I do miss having the correct speed and some other gagues, but a gauge pod and no electrical issues is a worthwhile replacement.

 

[kevincolyar]

@mojito5000 what kind of issues did your cts cause? I have the CTS3 (no juice) and the resetting of the factory stereo clock (when the truck is cold) is the only negative affect to the truck I've come across so far.

 

[mojito5000]

@kevincolyar it was all over the place for me. It started with the fuel gauge would read off the chart until I reset the CTS/Juice, some times I would get a no start, other times it would randomly die. I think my issues were more related to the Juice module, but I couldn't figure out how to get the CTS to work without the Juice so I just removed the whole thing.

My cousin runs the CTS2/Juice in his Cummins and has never had any issues. Talk to any shop and they will tell you to not un the Juice with Duramax trucks.

Does the radio still reset when the CTS3 is not plugged in?

 

[scott_willerscheidt]

Have you checked all 9 grounding locations?

2002 gmc sierra 2500hd quad cab short bed
Zone 3" kit
285/70/17 Nitto Terra Grapplers
17x9 Raceline 930's
S&B intake
3" turbo horn
PPE boost valve
MBRP 3" downpipe
MBRP 4" exhaust
HSP hot/cold side pipes
LED conversion
Edge CTS2 with SAS EGT probe
boost auto towing mirrors ( dual function)
fass 90
EFI live spade jack
dmax store stage 3 allison

 

[kevincolyar]

@mojito5000 it doesn't reset the radio when CTS3 is not plugged in. It also won't reset it when the truck is fully warmed up when I start it, and the CTS3 is plugged in. I assume it has to do with the cold weather and glow plugs.

@scott_willerscheidt I've checked and cleaned the grounds I could find (I know the frame ground under the driver side door is a common issue). I'm not sure how to find where all 9 locations are. I also replace all four battery bolts and cleaned the wire terminals.

I've noticed in these cold mornings when I first start the truck:
1. I'm at about 11.8V or so right after it starts
2. The radio is normal and the CTS3 is starting up
3. Right when when the CTS3 shows something like "starting data logging" the radio clock resets.
4. Maybe 10 seconds later I'm above 12V, then a few moments later, say when I take off, I'm at 14.3V when the alternator is charging.

I'm still waiting to hear from Edge. It's probably just a coincidence but this started happening with the latest CTS3 update but it's also when it started getting cold here.

My guess is the the glow plugs and the CTS3 "starting data logging" is pulling just enough current from the radio to reset it.

 

[mojito5000]

Since it does it only when the CTS is plugged in I would say that pointes to your issue there, even more so since it happened after a software update. If you keep your Edge, my advice is find a good version and stick with it. I updated mine just before a day trip out and ended up unplugging it half way through the drive.