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Grid Heater Stuck On

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This morning, I was in the drive through to pick up a coffee. I shut truck off so they could hear me through the intercom, and then turned truck on and waited in line. I could hear the grids turning off and on like normal. After a couple minutes, I hear it engage one last time l, but didn't hear the truck return to normal(still sounded like there was an electrical load.) Sure enough, im watching my volt meter drop and not go back to normal. Waited about a minute and then shut the truck off. turned it back on, no issues. Grids cycled and everything was good.  Does this sound like a relay problem?

 

Also id like to ask you guys this question. So if i let my truck warm up a few minutes while I sit in it, I manually raise the rpms(somebody needs a high idle kit🙂) if I go above 1100 or so rpms, the grid heaters kick on and stay on until it detects the rpms are back at idle, then it cycles normally. Is this a normal thing? 

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  • Mopar1973Man
    Mopar1973Man

    Need to watch your IAT temperature. As you increase the RPM the IAT typically falls off so the ECM holds the grid heater on longer. Hence why I normally don't high idle my truck I start let it idle ma

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Mine always cycles on and off whether I am at normal idle or high idle.  Your's don't sound normal.  I don't think you would want your grid heaters to stay on that long.  Things will start to get really hot... :ahhh: 

Even with higher RPM it should kick back off. It uses a bit of guessing and the IAT and coolant sensor to figure out if it should run the heaters. Next time it does it, maybe tap the relays with a wrench or something and see if they are sticking. It doesn't sound like sticking relays. If it isn't that, something with the IAT or the computer is telling them to stay on. 

 

What are you outside ambient temperatures?

  • Owner

Post heat is controlled by the battery temp sensor and the IAT but more so the battery temp sensor. 

 

As for suck on check the solenoids and see if the power is still applied to the trigger while stuck on. If so the contact arced together and fused. 

  • Author

@That Guy-mid 30s in the morning. ill try tapping the relays next time it happens..

 

as for the grids not shutting off when i idle it higher, im not sure what the deal is. Its done that since I noticed it a few years back.. this is from this morning. Above freezing, probably around 35 this morning.

 

Idles fine, but add rpm(past 1100 or so) stays on until I let off the pedal. 

 

 

I had to cut the video to make it fit, but I had it idled there for about 10 seconds when the video starts.

  • Owner

Need to watch your IAT temperature. As you increase the RPM the IAT typically falls off so the ECM holds the grid heater on longer. Hence why I normally don't high idle my truck I start let it idle maybe 30 to 60 second to sling oil on everything. I get rolling once you hit 20 to 25 MPH the grid heaters should be forced OFF!

    • Like 1
    • Author

    I pretty much do the same as you @mopar1973man. If its cold cold, I'll jump the rpms up to just below 1100 for a minute or 2 before i take off. Grids shut off after I hit 20, all is good. 

     

    So ill keep an eye on the grids sticking on at random, ill try tapping the relay if it happens again, and then go from there. I dont thing relays are to expensive to replace right?

    • Owner
    5 hours ago, Alexio Auditore said:

    Genos has them a bit cheaper at 53 bucks. Probably the route I'd go. No repeated issue thus far tho. Still waiting..

     

    https://www.genosgarage.com/product/dodge-ram-cummins-grid-heater-relays-with-bracket-dorman-904308/winter

     

    Dorman's Engine Air Intake Heater Relays for '94-'02 Dodge Cummins trucks effectively controls the intake heater.

     

    https://www.amazon.com/Dorman-Solutions-904-308-Intake-Heater/dp/B00Z7O4M4Y/ (Cheaper yet!) $49.95

    Edited by Mopar1973Man

    21 minutes ago, Royal Squire said:

    Hard to beat free shipping!

    It's a consideration, for sure, but I don't put Dormant and Standard in the same quality category. 10% extra for Standard is worth it to me - dealing with RA and their love affair with FEDEX may sway me back to Dorman and Amazon.

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    Welcome To Mopar1973Man.Com LLC

    We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features.  Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.