Grid heater staying on

[Gregturley]

I did the grid heater controller that i think MAYBE @IBMobile wrote up. Have had it switched off since spring.  Everything was good. I lost a hydroboost and a gearbox this summer and completely covered everything under my hood in power steering fluid. Now its cold in Loserville ky and and i need the grid. My problem is when i turn my switch on the grid stays on all the time. Never shuts off until i flip the switch. 

 I will admit i have not had the time to put it back to factory stock conditions to see what happens. Scan tool shows nothing.

 Any help/ideas are really appreciated. 

 Thanks guys.

[IBMobile]

I wrote two ways to control the grid heaters; Grid Heater Bypass and Grid Heater Bypass Simplified.   Which one did you use?

 

 

Edited December 18, 2021 by IBMobile

[Gregturley]

'Honestly i do not remember.  I do remember me and you had a back and forth about the solenoid having a diode protect on it. I Had said if it was done strictly your way it would be fine but if you did what I did and tied multiple things on same circuit it could have issues.  It was based on what kind of electronics were after the grid shutdown.

 Again i am not wanting to cause issues.  I'm honestly trying to rember what changes I've made to this pig.

[IBMobile]

It sounds like the on/off wire from the switch got attached to one of the grid heater relays.  This is the way it should be installed with the power on/off wire from the switch only going to the relay terminal marked with an S.  

 

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/electrical/grid-heater-bypass-simplified-r662/

[Gregturley]

I don't remember what i did. I should have made better notes on this mod but i did not. Thanks for the link. I'll try to look into the issue tomorrow after my daughter leaves me. Raining and cold here now hopefully tomorrow will just be cold.

If my switch is on grid heater works. If my switch is off grid heater is bypassed. When i 1st did this if the switch was on it worked. Just like mopar intended. After the numerous ps/brake failures i had that ps fluid everywhere under the hood is when i noticed the issue. Before when it was cold I'd leave the grid switch on and it would work as Mopar intended it. Now if the switch is on the grid stays powered up and never turns off until i kill my switch. 

[IBMobile]

You may have a bad grid heater relay that's stuck closed.  There are two of them, one for each grid heater, located on the left inner fender below the battery.  Test by disconnecting the grid heater relays' ground wire, black with yellow tracers, this will the relays from turning on.  Next, with thew bypass switched on, turn the ignition switch to on. Test for voltage at the grid heaters; there should be no none.  If there is voltage to a grid heater, then that relay is bad.

[Gregturley]

Will check that thank you

[Gregturley]

Ibmobile@ what i did was used the relay you wrote about using along with a switch. For some reason now my grid heater stays on whenever my switch is on.

[IBMobile]

 

Power flow: battery positive to solenoid to grid heater relays to grid heater.   The switch you installed controls the solenoid for battery power to flow to the grid heater relays.  The grid heater relays have to be energized by the ECM for power to flow to the grid heaters.  If power is flowing all the time to the grid heaters with the switch on and the engine off, then a grid heater relay is stuck on.  Or did the grid heaters get connected to the solenoid by passing the grid heater relays?