DrJeff

I'm new to posting, I opologize for sounding like a newbie but I AM.... 97 4x4 Laramie Long Bed, No Mods...I have a check engine light that comes on during morning starts. The Volt meter reads low 8-10 volts for approx. 30 seconds then goes to 14 volts and fluctuates back and forth until engine warms up. I though it was an alternator issue and replaced it. It seemed to fix it for a couple days then it started again. I have had Dodge run a scan on it (unimpressed!) they stated that it might be a Heater Sensor, a $600 fix, and if that didn't fix it then they would have to try looking at other areas which may lead to a $2-3k fix. The truck runs great. Morning temps in CA are 50 to 60 degrees, if that matters.

I purchased this vehicle used with 235K mi on it. I now have 252K on it and have realized the previous owner poorly maintained the vehicle, a learning experience for me! I am new to diesels and am looking to purchase a HO 600 within the next two weeks.

I am getting ready to sell this truck and would like to have it mechanically sound for the next owner. Any info is appreciated!

RCW

The voltage fluctuation is normal for this engine while it warms. It is the grid heaters in the manifold cycling, and possibly the fuel heater kicking in until the engine is up to operating temperature.

The cycling tells me that the PCM is reading the temperature and sending its commands to the heater solenoids just fine. However, if the check engine light turns on and stays on until the engine is hot, replace the coolant temperature sensor. It is a few dollars and very easy to change yourself.

If the check engine light comes on and stays on, then get concerned. If it comes on and then goes out before the engine warms, it either is reading a ghost or the problem is correcting itself, or the engine coolant sensor is starting to fail.

DrJeff

...If the check engine light comes on and stays on, then get concerned. If it comes on and then goes out before the engine warms, it either is reading a ghost or the problem is correcting itself, or the engine coolant sensor is starting to fail.


The Check engine light does stay on until I disconnect and reconnect the batteries. The Check engine light only trips in the morning.

Haulin_in_Dixie

He might have weak batteries causing the check engine to come on from too low a voltage with the heaters on. It does sound like the heaters are a little overactive though for the temperatures he mentioned.

KATOOM

Mine will cycle too in temps like that. Sounds OK but if it went away for a short time maybe you have a bad battery. I've seen many a problems caused by batteries. They dont have to be dead to be bad. I would have it scaned though and find out what code you have. Another thing with the OBD 2 system that these vehicles have these days is if you throw a code and the problem goes away within a certain time frame then it will turn the check engine light off.

4doogie

my 97 has the same prob. i took it to dodge and they fixed it and two weeks later it came back on, its been like that for 20,000 miles and the truck runs fine. it goes off from time to time and when i have time i will take it to a cummins shop and have them look at it.

jaconst

I am getting ready to sell this truck DrJeff
is it a club cab? how much are you asking and whats the info on your 97?

J BODY

If you can get the exact P code that is storing in your computer. A "heater sensor" is a bit vague. You will enjoy the power of your new truck when you get it, but your 97 most likely will spin circles around it in the miles per gallon department.

DrJeff

is it a club cab? how much are you asking and whats the info on your 97?jaconst

It is a Club Cab, 4x4, Lariat, full power, 3:54, White, CA model, 252K mi, stock with exception to K&N. From research in my area, they're ranging from $11K to $16K. I am asking $13K.

DrJeff

If you can get the exact P code that is storing in your computer. A "heater sensor" is a bit vague. You will enjoy the power of your new truck when you get it, but your 97 most likely will spin circles around it in the miles per gallon department. J BODY



I did have it checked at Dodge but I didn't get a copy of the codes. They had the codes and were vague about what it could be, they seemed to want to trial and error it to find a fix on my dollar ($600-$3K was their estimate) and that is why I am here. After doing some reading and listening to what has been said I am leaning toward replacing the air temp sensor and coolant temp sensor.

scuzman00

Go to your local Auto Zone or similar auto parts store and have them pull codes from OBD plug. Come back in here and do a search on diagnostic codes and you can tell exactly what codes the dealer pulled up. Do not pull the battery cable disconnect trick to clear the check engine light, in that you may clear codes from PCM.

Good luck and let us know what you determine.

Gary

J BODY

What Scuzman00 said. Get us some "meat and potatoes" info before letting us decide how to spend your money! If indeed it was a "intake air temp" issue, I see from your explanation I see you said "California truck". Safe to say it has EGR then? With the high miles you may just have to remove the inlet air temp sensor and clean it as EGR equipped trucks pollute them pretty good. Get the "P code" and we'll see what we can do for you.

DrJeff

J BODY, I think you hit it right on the money, I pulled the Intake Air Sensor and it looked like a Kingsford was hanging off the end. I cleaned it up and so far No Problem.

Thanks everybody for all the help.

J BODY

Gold star for you!!

4doogie

this is a stupid question, but where is the intake air sensor? is it on the EGR? how long does it take to fix it?