Engine/Transmission (1998.5 - 2002) Grid Heater Cycling

[Phil Stuart]

eliminating post heat cycle

Originally posted by WeirCummin

I did come up with a simple fix for the GH It will only let them cycle when the engine is not running=no oil pressure





Here is what I did to stop the cycling of the GH.



Get yourself a Borg Warner S320 oil pressure switch, it is N. C. (normally closed, open on rise) or equivalent. There is a port on the oil cooler/filter assy, 1/8" NPT.



For the wiring, it is only the control ground circuit that you are breaking so 16 to 20 gauge wire will work. From the switch you'll want to run a wire to both of the ground terminals on the GH solenoid coils. They are the two that are towards the firewall on each solenoid. The wire can be run in series since the factory wiring is done the same way.



Dean [/B]

I did the fix the other day. Went to NAPA and the parts guy cross referenced the number (can't remember right now) but the fix works great. I think this is an excellent idea, the grid heaters now only do a pre-heat cycle. No more dimming lights and voltmeter dropOo.

Thanks for the great ideas!



Phil

 

[Tomscreek]

Mine cycles even after a 12 mile drive to work and engine temps are up. I noticed this after I shut it off and then restarted... . this was at idle but warm engine, outside temp about 15 degrees F.

Is this normal? If so I'm going to look into one of the above mentioned kits.

 

[Phil Stuart]

Post heat cycle

Originally posted by Tomscreek

Mine cycles even after a 12 mile drive to work and engine temps are up. I noticed this after I shut it off and then restarted... . this was at idle but warm engine, outside temp about 15 degrees F.

Is this normal? If so I'm going to look into one of the above mentioned kits.

Yes It's normal and it is the Intake Air Temp. sensor that's making the heaters cycle even after the engine has warmed up.

It's sensing the cold air and telling the heaters to kick in.

They will shut off after 90 sec. I believe or 18-20 mph.



I like the fix and It's cheap!



Phil

 

[ToolManTimTaylor]

Originally posted by Steve St. Laurent

Just a guess Doug but do you still have that wire clipped for the speed limiter? Maybe that same wire is used to sense road speed for the grid heaters?

Man he found it I was gonna mention that as well ... . You know what they say ..... great minds ... .

 

[KenHokie]

quote:

--------------------------------------------------------------------------------

Originally posted by WeirCummin

I did come up with a simple fix for the GH It will only let them cycle when the engine is not running=no oil pressure



Here is what I did to stop the cycling of the GH.



Get yourself a Borg Warner S320 oil pressure switch, it is N. C. (normally closed, open on rise) or equivalent. There is a port on the oil cooler/filter assy, 1/8" NPT.



For the wiring, it is only the control ground circuit that you are breaking so 16 to 20 gauge wire will work. From the switch you'll want to run a wire to both of the ground terminals on the GH solenoid coils. They are the two that are towards the firewall on each solenoid. The wire can be run in series since the factory wiring is done the same way.



--------------------------------------------------------------------------------



WeirCummin, Great Idea! I went to my local NAPA store and they crossed the S320 to a napa part. The only problem I had was fitting the oil pressure switch onto the top of the oil filter assy. I have an auto and there are two cooler lines that are very close to the top of the oil filter assy. I needed to use a 1/8" NPT 45 deg street elbow (M - F). This little fix works great , no more dimming lights and unnecessary heater cycling. I plan to add a 3 position switch to the dash so that I can either turn the heaters completely off (for starting with low batteries), cycle them thru the oil pressure switch, or run them as factory. This forum is great, the GH cycling has been bugging me since I first got the truck. Not anymore! Oo.

 

[JohnE]

Originally posted by barbwire

hey fellows, I guess I never thought that the grid heater cycling until warm up would harm anything. Can anyone let me know what harm it does? Mine cycles until fairly warm also.

It doesn't do anything <em>bad</em> except annoy some drivers. I'm guessing that Cummins/Dodge increased the grid heater run time due to the cold blooded nature of the 24 valve at low engine rpm.



Is the moral of this story, drive don't idle?



-John

 

[pcarlson]

The grid heaters are not supposed to cycle till your engine is warm while your driving.



Pre Heat Cylce - temp dependent usually 30 seconds or less.



Post Heat Cycle - no more than 190 seconds.



Post Heat will shut off if vehicle speed goes over 18 mph.

 

[Texas Diesel]

Originally posted by pcarlson

Post Heat Cycle - no more than 190 seconds.

Neither my 98 or 01 did that, they would cycle endlessly until a certain speed was reached (if it was cool/cold outside), that's the problem. It appears that some function as you describe and some dont

 

[pcarlson]

It appears that some function as you describe and some dont

If some function with a post heat cycle of 190 seconds and some don't, then I'd tell Dodge to fix it. It's ECM controlled so reflash it or replace it if it's under warranty. That's a needless load to leave on the electrical system. Unless this is a brand new feature for the 02's.