Will glow plugs work (manually) if fusible link bad?

rholmes69 · Jan 7, 2020

'04 2810 here. Timer relay clicks, no light on dash. I pulled apart the power relay (located in front of air cleaner right above the battery) and manually closed the contact. Held closed for 10 seconds, released and turned key, she fired right up. I hadn't noticed the problem since replacing the positive battery cable last year. I didn't check the fusible link, and the new battery cable didn't have the second little 10g or so wire coming off the positive terminal like the old one did. so my question is will the relay work when manually closed (like I did) if the fusible link is bad? Or does power have to flow through the fusible link to get to the relay.....

Thanks!

shovelmike · Jan 7, 2020

I haven't seen a wiring schematic for that one, but it appears that what you did bypassed much of the circuit, possible including the fusible link. Your method works until you can see how it's wired, I hope the verbiage in the service manuals is clearer than in the owner's manual. It appears that they picked an employee who sort of knew some English.

JerryK · Jan 7, 2020

I ' would think ' that if the fuseable link opens up, there would not be power going to the relay. ' Most ' fuseable links are near the battery, in the cable coming from the battery to the devise. Most are wired battery, fuseable link, relay, then the power going thru the relay going there to the heaters. But, just a guess on my part without a print, and most prints are questionable, too.

[ Sometimes the relay contain a small circuit board with a timer in it to operate the relay, and you might find just some cracked solder joints around some component. That is what usually happens, the solder fails after the component CLICKS on/off X amount of times. ]

skipmarcy · Jan 9, 2020

Yours is probably the same as my 4110. The timer is in the dash of mine, it doesn't use a fusible link in it's circuitry, just fused (fuse box) power. The relay on mine is the same as yours and is out in front of the air cleaner and the on/off of the relay is what is controlled by the timer and is not powered by the fusible link. When the relay is powered on by the low amperage circuit from the timer, it closes the switch inside the relay that powers the higher amperage circuit that actually powers the glow plugs. This circuit is the one protected by the fusible link only. Since you energized the relay manually and the glow plugs worked, that means the fusible link and associated wiring and relay are good. If you so desired you could eliminate the timer circuit by using a switch to turn the relay on/off manually. Be sure to use fused power to your switch for safety purposes. Usually the 2 wires for the control circuit of the relay are smaller gauge than the heavier 2 wires for the glow plug circuit. 1 control wire will go to a good ground, the other will go to your switch for power.

radios1 · Jan 9, 2020

why not just put a connector on the battery to power the fusible link, so it works like normal?. why redesign the circuit for no good reason?.

skipmarcy · Jan 14, 2020

radios1 said:
why not just put a connector on the battery to power the fusible link, so it works like normal?. why redesign the circuit for no good reason?.

His fusible link is already connected directly to the battery and this part of the system IS working, I suggested eliminating the timer circuitry that engages the glow plug relay if he so desired. When the key switch is turned counterclockwise it starts the timer to engage the glow relay, on mine for approx. 20 seconds. My suggestion was to replace the timer control with a simple on/off switch that the operator controls how long the glow plugs stay on. I think those timer relays are a little pricey from Mahindra whereas a simple toggle switch would be a less costly and more dependable repair. If mine ever craps out that's what I'll do.

radios1 · Jan 14, 2020

skipmarcy said:
His fusible link is already connected directly to the battery and this part of the system IS working, I suggested eliminating the timer circuitry that engages the glow plug relay if he so desired. When the key switch is turned counterclockwise it starts the timer to engage the glow relay, on mine for approx. 20 seconds. My suggestion was to replace the timer control with a simple on/off switch that the operator controls how long the glow plugs stay on. I think those timer relays are a little pricey from Mahindra whereas a simple toggle switch would be a less costly and more dependable repair. If mine ever craps out that's what I'll do.

I'd use a momentary on toggle or pushbutton, since turning it off can be too easy to forget!..