Grid heaters not getting voltage

[Gordon Maney]

On 2003 3500 with 5. 9 Cummins and automatic transmission, the grid heaters cycle after the engine starts and runs. Voltage is measurable at the heaters.

If, before starting, you turn on the key and observe the wait to start light, the light does come on, and does go off after a while, but no voltage is applied to the grid heaters.

What could cause that?

 

[Bill Weber]

What is the temp? Should the heaters come on? If so have you checked the voltage at the solenoids and the at the grid? If no voltage there check the power to the solenoids. Also, check the voltage at the temp sensor on the intake manifold - if its not working then no signal to power the solenoids. Good luck.

Bill

 

[CKelley1]

if the temp is above about 50 degrees the ecm does not send the 12 volts to the solenoids. what you see is normal. most of us do away with the heaters. there is two codes that are set off if the heaters do not work one if the ait says it is cold enough and you have the key on and waiting to start and the ecm does not detect a voltage drop it throws a code. if the ecm does not detect a load on the control wire to the solenoid it will throw a different code. when you remove the grid you can either leave the solenoid connected to the control wire or remove and replace with a 35 to 50 ohm resistor. for the other code just do not wait to start. the heaters are not used on the industrial or equipment 5. 9's and cummins sells the block that is used on them. part #3922484. if you want pretty fbd, glacer, winspeed and others make them. the heater is a smog reduction thing our trucks will start twenty degrees below zero with out it. that is the coldest i have decided to go somewhere.

 

[Gordon Maney]

What is the temp? Should the heaters come on? If so have you checked the voltage at the solenoids and the at the grid? If no voltage there check the power to the solenoids. Also, check the voltage at the temp sensor on the intake manifold - if its not working then no signal to power the solenoids. Good luck.
Bill

It is a temperature when the heaters should come on.

After a cold start, there is a voltage to the heaters. Prior to a start, as the light is on, there is no voltage.

 

[Gordon Maney]

if the temp is above about 50 degrees the ecm does not send the 12 volts to the solenoids. what you see is normal. most of us do away with the heaters.


there is two codes that are set off if the heaters do not work one if the ait says it is cold enough and you have the key on and waiting to start and the ecm does not detect a voltage drop it throws a code. if the ecm does not detect a load on the control wire to the solenoid it will throw a different code.

when you remove the grid you can either leave the solenoid connected to the control wire or remove and replace with a 35 to 50 ohm resistor. for the other code just do not wait to start. the heaters are not used on the industrial or equipment 5. 9's and cummins sells the block that is used on them. part #3922484. if you want pretty fbd, glacer, winspeed and others make them. the heater is a smog reduction thing our trucks will start twenty degrees below zero with out it. that is the coldest i have decided to go somewhere.

These attempts are below 50, more like 30 degrees F.

How do I retrieve the codes? Is it like my 2001, you turn the key on and off multiple times and then leave it on?

I am interested in your comment that the heaters are not needed. They certainly seem to help my 2001, as I cycle them multiple times in very cold weather prior to a cold start. Why do people choose to take them off? Better air flow?

What is the AIT?

This truck cranks quite a while on a cold start, something it did not do before.

 

[JJPage]

Check for codes by cycling the key on/off 3 times without starting, on the third time leave it in the on position. Codes if any will appear in the odo bar.



This sounds very familiar with a different post, not too long ago...



If any codes pop up relating to intake heater performance, it is possible your start batteries are starting to fail, and the ecm recognizes this and does not allow voltage to the grid heaters until it starts. I believe this is what I remember, let us know about the codes.

 

[Gordon Maney]

Check for codes by cycling the key on/off 3 times without starting, on the third time leave it in the on position. Codes if any will appear in the odo bar.

This sounds very familiar with a different post, not too long ago...

If any codes pop up relating to intake heater performance, it is possible your start batteries are starting to fail, and the ecm recognizes this and does not allow voltage to the grid heaters until it starts. I believe this is what I remember, let us know about the codes.

Ooooohhh. Neat. Fascinating and plausible. I am hoping that is it. I will see about getting the codes and find out the history of the batteries.

Thank you... .

 

[jelag]

Is there a chance that you have your test light grounded to the battery (-) and your touching the wrong side of the grid heater and that's why your light is not coming on??

 

[Gordon Maney]

Is there a chance that you have your test light grounded to the battery (-) and your touching the wrong side of the grid heater and that's why your light is not coming on??

I don't mind that you ask, but no, I am not doing that.