Good video-- I have opened them up. Inside is a MOSFET controller (running off 5v ecu signal) ...it also has a diode and an input resistor. Mosfets are like a solid state relay---and the signal allows voltage to activate the relay for the glow plugs. While MOSFETS in theory are "high impedance with no current flow" devices--they do in fact use capacitance to control the high current flow used to operate the coil. If the resistor wasn't there--the coil would draw over over 20 amps of current for about 1 second while the capacitor charges--it would draw it thru the ECM and probably fry it. without the diode--the backcharge from the coil would also cause damage. The coil itself measures about 8 ohms of resistance. Luckily, the unit basically fails "off" if diode etc fails. I have always wanted a slightly longer glow plug time to compensate for the change from 9G glow plugs to the current ones. The old 9g's lit up about 3 seconds quicker than the new ones. However, the ECU has no idea what plugs you have---so the GP's are chronically "short timed"--which is one reason why the 6.5 always seems harder to start in cold weather. So..I'm using a solid state programmable relay that adds 3 seconds of "on time" to whatever ECU signals. This is an immense improvement in really cold weather --ie--20 F or below. I have installed it...but not sure its ready for prime time as its pretty delicate for the environment under the hood...we'll see.
You're one hell of a good mechanic MND! Always testing and troubleshooting properly before executing the repair. Are you self taught? Have any gray haired mentors?
When you tested it ,it has a time intervals to cycle the glow plugs.How did you check for power on the harness in time ? How is the cycle timing turned on and off ? Where does the timed cycle come from,the cpu ? Or something else ?
Your knowledge is pretty freakin' amazing! "We'll see what breaks tomorrow" - lol. Nice to see you've kept your sense of humor. I would've have run the truck over with a bulldozer by now.
You have no idea.. I don't think I have had a single day yet where something doesn't break. I just have to figure it out to keep it running and hopefully I am able to run it without a problem soon. I just had an oil cooler line spring a leak last night and drove home with very little oil. Fixed that though.
Ive had a no start no glow plug light on issue and found a fuse missing from the #4 fuse holder in the driver side dash.I was checking fuses before that because I blew the cab light fuse abd was trying to find which one it was and somehow lost the # 4 fuse and didnt relise it.Somehow my # 4 fuse controles my glow plug relay abd dash light ?
Thank you for the video. My 93 I have now power at the dashboard so I hope the glow plug relay is my problem.
Glad it helped. Hope you got it figured out
Good video-- I have opened them up. Inside is a MOSFET controller (running off 5v ecu signal) ...it also has a diode and an input resistor. Mosfets are like a solid state relay---and the signal allows voltage to activate the relay for the glow plugs. While MOSFETS in theory are "high impedance with no current flow" devices--they do in fact use capacitance to control the high current flow used to operate the coil. If the resistor wasn't there--the coil would draw over over 20 amps of current for about 1 second while the capacitor charges--it would draw it thru the ECM and probably fry it. without the diode--the backcharge from the coil would also cause damage. The coil itself measures about 8 ohms of resistance. Luckily, the unit basically fails "off" if diode etc fails. I have always wanted a slightly longer glow plug time to compensate for the change from 9G glow plugs to the current ones. The old 9g's lit up about 3 seconds quicker than the new ones. However, the ECU has no idea what plugs you have---so the GP's are chronically "short timed"--which is one reason why the 6.5 always seems harder to start in cold weather. So..I'm using a solid state programmable relay that adds 3 seconds of "on time" to whatever ECU signals. This is an immense improvement in really cold weather --ie--20 F or below. I have installed it...but not sure its ready for prime time as its pretty delicate for the environment under the hood...we'll see.
You're one hell of a good mechanic MND! Always testing and troubleshooting properly before executing the repair. Are you self taught? Have any gray haired mentors?
I've had a few good mentors here and there but never went to school for any of it. Just UA-cam University.
BTW--that old motorola box is a "hands free" cell phone box for very very old flip phones....lol
When you tested it ,it has a time intervals to cycle the glow plugs.How did you check for power on the harness in time ? How is the cycle timing turned on and off ? Where does the timed cycle come from,the cpu ? Or something else ?
Entonces ese relay que reemplazaste es quien controla el tiempo de calentamiento si o no , o lo realiza la computadora?
Computer controls the time based on the temp sensor reading
Your knowledge is pretty freakin' amazing! "We'll see what breaks tomorrow" - lol. Nice to see you've kept your sense of humor. I would've have run the truck over with a bulldozer by now.
You have no idea.. I don't think I have had a single day yet where something doesn't break. I just have to figure it out to keep it running and hopefully I am able to run it without a problem soon. I just had an oil cooler line spring a leak last night and drove home with very little oil. Fixed that though.
@@MNDashcam See? "Fixed that though". I rest my case ;-)
Ive had a no start no glow plug light on issue and found a fuse missing from the #4 fuse holder in the driver side dash.I was checking fuses before that because I blew the cab light fuse abd was trying to find which one it was and somehow lost the # 4 fuse and didnt relise it.Somehow my # 4 fuse controles my glow plug relay abd dash light ?