Lights On My Truck
 

so my truck is driving me insane and annoying the crap outta me lol. While ideling, driving and even after the truck is warm the headlights will dim then brighten back up and so do the interior lights. The truck has always done this but only when it was cold and the heater grid was cycling now its almost every time I drive and for the whole time im driving. Does anyone have any ideas????

yer grids are kicking on causing a high amprage draw

I always wanted to put a pressure switch in so when it saw oil pressure it opened the loop on the grids............once the motor sees oil pressure wala no more grids

why would they be kicking on though after I have allready been driving for over a hour and the truck is warm?

thats a good question..............and it dont even get cold in Texas either


I honestly dont know where it gets its temp reading from but oyu have some kinna problem there

is it the sensor that in the intake tube just after the filter?

yea I drove a pretty good distance last night and the truck never did it from the time I left the house and all the way there and never shut the truck off but the whole freakin way back I had to look at my headlights going dim and then bright again. I really felt like getting out and shooting them lol

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shoot you got me I didnt know I had one there? lol

what was the ambient tems last nigh there?????

I found this pic and circled yer inlet temp sensor....................I still dont know if this is where the grids gets its reading from.........but I would bet it is

Does the IAT sensor come into play here? What makes the grid heater cut in/out? ECM?

Hmm you just beat me to it Whitmore....

scratch that...........I thought yer truck was newer.................I guess I dont know on a 99.....there is no sensor on the air inlet on a 99


maybe its in the intake manifold ????


AIT sensor maybe...............Bingo I think we have a winner

AIT is back of the motor drivers side just below injector #6

Sometime today, I will try to find my service manual and have a peek for you Bia...

Ok I will check that I guess when it stops raining if not Im taking my headlights out lol

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ok thank you much.

With my luck its probably some rare sensor that is on back order for 6 months and cost 500.00 lol

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[lukesdiesel] The heater system consisted of the air-heater unit mounted on the intake manifold cover, the microprocessor mounted on the left side of the dashpanel, two relays on the left inner splash shield, and a temperature sensor in the intake manifold.

luke informed me of this so I guess its more than one spot that could be bad

IAT Sensor....(Intake Air Temperature) :ph::ph:

The more I think about it, this seems to be the problem.


Heres some info for diagnosing the sensor:

http://www.dodgeram.org/tech/dsl/sensors/IAT/clean.htm

Give it a good cleaning with some electrical contact cleaner (or brake cleaner if you are in a pinch) and see what happens. This thing isnt real easy to get to - you will likely have to lay on the valve cover.

They are not expensive either...

The IAT sensor measures the temperature of the intake manifold. The ECM uses this sensor reading to set injection timing and adjust the air-fuel ratio. If the fuel mileage and power output of you engine seem low, some owners have found improvement in EGT, fuel economy, and power after cleaning carbon from the IAT sensor in at the rear of the intake manifold. Engine with exhaust brakes are particularly prone to IAT sensor fouling because soot is blown back into the intake during valve overlap. Smokingdiesel.com has an information page about problems caused by the IAT sensor.

The only tool you need is a 3/8" ratchet with a 6" extension and 13/16" socket.

The IAT sensor is found on the driver's side of the engine, almost at the back of the intake manifold.




Temperature
Resistance

30°
40K

32°
30k to 36k ohms

76°
13K ohms

77°
9k to 11k ohms

81°
6.87K ohms

122°
3k to 4k ohms

130°
4K ohms

167°
600 to 675 ohms

212°
600 to 675 ohms


Replacement Sensor:

Cummins PN 3408345

Dodge PN 05014197AA Sensor, Temperature (SEN, TEM)

here is a pic of the lil buger too

allright cool thanks alot now my headlights can live lol. Once it stops raining I will go outside and clean it up and see what happens. Hopefully thats all it needs

Let us know how you make out.....

Bia, Ive been thinking about this a little...There are two relays that control the grid heaters - they are on the drivers side fender. Im thinking that one of them is bad.

Intake Heater Relay

This is for a 12V I dont know about the 24V

Update???

no I have been busy my grandfather passed away and his funeral was today. I planning on getting up in the next few minutes to go give it a good cleaning.

My condolences Bia...

one thing you could try is since it never gets cold in TX you could unplug the 2 control wires that go to the solonoids. you should have 2 wires per solonoid that is bolted on and then 1 that is in a 90* connector that slips on (like a starter solonoid on a Ford gasser), this is the wire to dissconnect. that would comepletely take the grid heater out of the conclusion unless a solonoid is bad and still making it dim. doing that you should be able to reference ground to the battery and probe the solonoids 2 remaining wires. one side of the solonoid should have 12v and the other side should read 0v with that control wire removed. do this on both solonoids. if this keeps the lights from dimming then that narrows it to the grid heater relays, IAT, or any other electrical problem.

Doc..... i doubt that it would be the solonoid being bad because if it was it would drain the battery in a heartbeat or melt the wire insulation when the truck isn't being driven, i'd bet on the relays myself having the control circuit shorted or a sticky contact inside staying latched..... i could be wrong but that's what i thought.. but then again it won't come on unless the air temp is cold enough.......hmmmmm what part in the circuit is controlled by the speed? this to me almost seems to be the problem as it should quit cycling no matter how cold the motor is once you reach 15-25 MPH.....

It seems there may be some confusion between the 12V and 24V trucks. I believe the grids work somewhat differently.

Bia, if the Iat doesn't work you can live without the grid heater here, I know for us its been cold the past few days but our trucks can take it alot better than we can, I unhooked mine to see how it would do, before I buy the spacer plate, and its been firing right up since this strong front came through.

doc i added some info.... i forgot to refresh the page before i edited..... how's the difference on the 12 and 24v trucks? pics would be nice if that's what you are talking about since you have one of each that might help..... also are the heaters controlled by the comp on a 24v?