Glow Plug Timer control units

dippa · Sep 3, 2015

Thanks for your replies. Forgot to mention earlier that I already tried to replace diode D3, but it didn't change anything. I also measured that blue resistor today and that was also ok (despite that looked a little bit overheated).

Here is glow relay wiring schematic from workshop manual:

If I'm reading that correctly, wiring looks same than SG51Buss's pictures, so that S85-NC should work also ok on my excavator? Or does that extra pin on timer really needs some signal from temperature sensor? Glowing time is of course different in S85-NC timer than my previous, but I think that is not a issue in real life...

skyhook · Sep 4, 2015

I would think it would need a signal on pin 5,
theres not that much on that board, bring it in to a tv repair shop etc, or if you can, replace the transistors and capacitors, check all diodes, looks like theres a few zener diodes, check those also.

The Fred · Sep 4, 2015

Mouser.com has every component very cheap to purchase for those repairs.

Fred

JRobyn · Sep 8, 2015

With no connection at all to the engine temp lug, the timer would either give you max on time or min (I don't know which), but should work either way.

- Jay

Don H · Nov 5, 2015

Glad I found this thread!

I have a 1988 Ford 1520 that has working glow plugs but the dash indicator light does not light when I key over to activate the glow plugs. I believe the problem is the timer but the cost from the dealer is $120!

I tested the timer as shown above. The test showed no power indicating the timer was bad. Figuring I had nothing to loose (except $120) I took the timer apart and cleaned it with contact cleaner, reassembled and now the light works!

I checked power to the glow plug while keyed over to the glow plug position, with the ignition in the ON position and in the START position. The glow plugs only work when the ignition is keyed to the GLOW PLUG position as they should.

I've read that others have tried the cleaning trick but it was only temporary. We shall see.

PILOON · Nov 5, 2015

My solution:
KISS
Heavy duty momentary switch capable of the amperage
or a relay + momentary push switch.

Push switch and count: thousand and one, thou and 2, etc for about 10 seconds and attempt a start, if no start count again maybe 15 secs.
She starts every time!

Cabanon · Feb 23, 2021

Hello, I know this thread is close to 6 years old now but this is the only place I found useful info regarding the glow plug timer relay. My dad has a Nissan N150 mini excavator with a S81NJ timer relay that I suspect is bad. I opened it up and all 4 caps inside were loose and desoldered. I thought this was very bad so I resoldered them all and tested it with the OP's method, but the light does not lit up at all. What I find very odd is the D6 diode make it impossible to have any current in position 6 as the cathode block any form of voltage/current to go through this pin. or am I mistaken ? I did tested all diode and all seems to be good.

I don't know where SG51Buss found these cool NGK diagram but I would very like to get one, if possible, for this model.

here's some pictures of the unit itself. maybe I'm missing something to check ?

aczlan · Feb 23, 2021

It looks like there's a Mitsubishi part MM431762 which crosses to that NGK part number which is available for $25 on eBay.
I might go that route if the components on the board all seem to test properly.

Aaron Z

Cabanon · Feb 24, 2021

yes this is also the other possibility. was looking to repair it as we order daily from mouser / digikey so getting the part and fixing it is not an issue. only downside from ordering on ebay is the lead time, but he's not using the excavator has it's winter time here.