grid heaters stick on

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I am a first time poster. I usually dont have to post anything because most times the information is already up on the forum. Funny how all these trucks seem to have the same problems but Dodge always insists "well it`s the first time we hear of this"...
My problem is:,my grid heaters were sticking on and killing my batteries so i cut the 2 trigger wires at the relay switches on the fender and wired them to a toggle switch. Works ok,not to kill my batteries but somewhere in the circuit the PCM thinks they are still active and keeps the alternator from charging,,,,if i turn it off for a few minutes it clears up. . Anyone have any ideas on this one,,i haven`t seen anything on this posted before. . Also if there is a way of divorcing the grid heaters so the PCM has nothing to do with them,,,manual control.
Thanks for your help.

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You should check your intake air temperature sensor. I recently saw something posted about someone else's going bad. I believe he said it was cheap and easy to replace. Your troubleshooting should start there. Hope this helps #ad

 

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Thanks,i will try that,,,would this be the little sensor in the top of the block,,just about the top of the fuel filter. ????
Thanks for your help.

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blacked out,96 3500,black,ext cab,KMC Slam,chrome aluminum wheels,continuous wheel balancers,Diesel Dynamics fuel plate and AFC kit,16cm housing,Dunnrite torque converter,Trans-go diesel shift kit,K&N filter,60 gallon transfer tank,Rld topper,

 

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Thanks,,i will try the temp sensor. Would this be the one on top of the head near the fuel filter???
Thanks for your help.

 

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The temp sender would be located in intake manifold(lower half). Right next to(in back of) intake manifold heaters going toward fire wall. Yes the fuel filter is close by.
As far has disconnecting from PCM the sensor is what send signals to the PCM. PCM turns on heater relays( I believe by giving them a ground, will look thru service manual to confirm).
But would be better to let PCM do it automatically.
Also look for wire shorting(grounding out), going to relays and sensor.

 

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Reread top half of post. Is voltemeter showing large discharge(8 volts) when you turn toggle switch on? Or is this when toggle switch is off?
I'll take it is when you turn toggle switch on to activate heaters.
It is normal for volts to drop to 8 when air intake heaters are on. The PCM cycles heaters on and off. When Vehicle reaches 10 mph PCM shuts down system.
Are you sure intake heaters were on? They should only activate when ignition switch is turned on(run position).
Check wiring from relays to heaters, relays to PCM,heck you mite as well check wires to sensor. Look for wires or connections that have bare wire(or pins touching) that could create ground or send power to heaters.

 

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Also, when driving at night, look for the dash lights and headlights 'flickering'. If this is happening, you probably have one or two failed relays, in which case disconnecting the control leads won't help.

The relays DC use are really cheap. The spring in one of mine failed, allowing the contact to bounce, causing the flickering. Finally, the spring gave up completely and let the heater stay on.

It is easy to tell if a relay has failed: remove the assembly from the fender and shake it lightly; if you hear 'clicking', the relay has failed. (The spring inside should keep the contactor from moving when the relay is 'off',)

Also, if you *have* had heaters stay on and drain the batteries, I would suggest you check the manifold connectors for melting and connection failures. Also, you want to check the air line from the manifold to the AFC. When mine failed, the plastic air line melted shut, thus causing the system to think there wasn't any boost, resulting in 0-60 times measured in hours.

In summary, if you have intake heaters sticking on, most likely you have at least one failed relay.

Fest3er

 

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A friend of mine, Artie, at Fairway Dodge (201)445-2541 had that happen to his former 96 2500. It was so bad that it almost started a fire. He knows the remedy for the situation and you can give him a call at the dealership. He works in the parts dept. Tell him Chris from Auto Wurks Diesel told you he remembered it happened to him.

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Chris Timochko
1997 5sp 4X4, HX40, BD 4" Brake, Marine Compression, Custom Tuned Injection Pump, Auto Wurks Diesel Intercooler, 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, Water Injection, NOS Diesel Kit, 6" Chrome Exhaust System, No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc, Goodyear Wrangler AT/S 305/70/16s. Test mule for Auto Wurks Diesel race program

 

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Thanks for the help guys. . And yes my AFC line did melt before. My relays have stuck on a few times before,which is why i rigged up a switch from the trigger wires on the relays so that if they did stick i could at least shut them off. . The last itme they stuck on the truck was parked and off,,drained the batteies in 20 minutes. Should i just replace the sensor,,or go for the relays too.
Thanks again.

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blacked out,96 3500,black,ext cab,KMC Slam,chrome aluminum wheels,continuous wheel balancers,Diesel Dynamics fuel plate and AFC kit,16cm housing,Dunnrite torque converter,Trans-go diesel shift kit,K&N filter,60 gallon transfer tank,Rld topper,

 

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Hooter,
Sensor doesn't seem to be problem it only recieves power whe ignition is turner on.
Your heater relays have direct power from battery at all times, check(test) out relays or just replace them.
Test, see if power is going thru relay to heaters when igntion is off. I think as the others have mentioned this is the problem.

 

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So it seems the only link in the heater grid system is the relays,,,,like i said,,,they drained my batteries before with the truck stoped... It seems evrybody`s recommendation is to just rplace both relays. . Any suggestions as to where the best or cheapest place to buy them??? Dodge or Cummins direct. If any one has prices i would greatly appreciate it...
Thanks again to everybody,,,this group has fixed practicaly everything i ever had a problem with.

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blacked out,96 3500,black,ext cab,KMC Slam,chrome aluminum wheels,continuous wheel balancers,Diesel Dynamics fuel plate and AFC kit,16cm housing,Dunnrite torque converter,Trans-go diesel shift kit,K&N filter,60 gallon transfer tank,Rld topper,

 

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I think you're stuck with a Dodge part unless you want to use a generic relay which will probably mean a bit of rewiring.