New here. I have a DK45SE that when the key switch is turned to the first position (where the glow plugs kick in) it blows the 60A main fuse. I just installed a new starter and a new key switch. It was doing this before the new components were installed. I disconnected the glow plugs and tested the circuit. Timer comes on, the glow plug light comes on for 15 seconds and 12v present at the plug. The fuse does not blow when the plugs are disconnected. I pulled all of the glow plugs and tested them. All at 0.8 ohms and tested on a battery for proper operation. For the moment I am running without the glow plugs connected and everything works fine. Any suggestions? Thanks in advance. There seems to be a lot of knowledgeable people here and a great community.
Fuddyduddy1952
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Glow plug resistance should be 1 to 6 ohms from what I looked up.
WinterDeere
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How many plugs are on this circuit? 0.8 ohms would draw 15 amps at 12 volts, if the resistance doesn't change much with temperature.
I'm no glow plug expert, but I suspect they're PTC = positive temperature coefficient. So your 0.8 ohms cold may indeed translate to Fuddy's 1+ ohm values when warm, and even less than 15A each once heated.
I suspect you may have a glow plug that's expanding and shorting when it gets hot. Check the data on your fuse part number, and you'll probably find you need several times 60A to cause the fuse to blow in any short time.
I'm no glow plug expert, but I suspect they're PTC = positive temperature coefficient. So your 0.8 ohms cold may indeed translate to Fuddy's 1+ ohm values when warm, and even less than 15A each once heated.
I suspect you may have a glow plug that's expanding and shorting when it gets hot. Check the data on your fuse part number, and you'll probably find you need several times 60A to cause the fuse to blow in any short time.
I have 2 good plugs that I picked up for spares and they measure the same. No time to heat up before it blows. I got some replacement fuses from Amazon. They were sold as slow blow but I don't think so. Guess zi just need to get a proper 60aA fuse but it still shouldn't pull 60A.
WinterDeere
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I think you're missing the point. A 60A fuse will typically take something like 300A to blow in 1 second, or 1200A to blow in 0.1 second. If you want more accurate numbers, consult the time/temperature curve for your fuse part number.
But ignoring the tedium of exact numbers, if you say they're blowing nearly instantly, you have a short circuit. If you're positive it's not in one of the glow plugs, then it's in your wiring. Period.
If disconnecting all the glow plugs prevents the fuse from blowing, then you know it's either a plug or the wiring in that branch of the circuit. I would disconnect all glow plugs, then reconnect them one at a time, until you find branch of the circuit blowing the fuse. Then you can swap out that plug to find out if it's the plug itself.
But ignoring the tedium of exact numbers, if you say they're blowing nearly instantly, you have a short circuit. If you're positive it's not in one of the glow plugs, then it's in your wiring. Period.
If disconnecting all the glow plugs prevents the fuse from blowing, then you know it's either a plug or the wiring in that branch of the circuit. I would disconnect all glow plugs, then reconnect them one at a time, until you find branch of the circuit blowing the fuse. Then you can swap out that plug to find out if it's the plug itself.
Fuddyduddy1952
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The glow plugs were in parallel. Four 0.8 ohm=0.2 ohms at 12.6V=63 amps.
Good troubleshooting advice from winter, simply connect one at a time.
An induction ammeter like this is handy because you don't have to disconnect anything. Back of meter has a slot you just put over battery cable or wire going to 60A fuse.
Current draw should be same for each glow plug.
Good troubleshooting advice from winter, simply connect one at a time.
An induction ammeter like this is handy because you don't have to disconnect anything. Back of meter has a slot you just put over battery cable or wire going to 60A fuse.
Current draw should be same for each glow plug.
WinterDeere
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Everyone complains about "made in China", until they need a cheap meter to get the job done:
Unlike the antique Amprobe clamp-on meters, these measure AC and DC currents. But being digital, they may not have time to even respond to a short pulling battery-level currents. Sometimes analog needles are nicer.
Unlike the antique Amprobe clamp-on meters, these measure AC and DC currents. But being digital, they may not have time to even respond to a short pulling battery-level currents. Sometimes analog needles are nicer.
Starter ground may be bad, so it's back flowing thru the glow plug circuit. Without the plugs wired in, it's finding another pathway. The 60+ amps is the starter load backfeed.
If so, disconnect the heavy wire from the starter, and see if the glow plugs work as they should. The starter won't roll, solenoid MIGHT try to pull in (also could be bad ground related). Another way to check would be to hook a grounding starter cable from the battery neg to the starter housing.
Just a wild guess. Couple of Fords with the woven grounding strap drove me nuts for a while.
If so, disconnect the heavy wire from the starter, and see if the glow plugs work as they should. The starter won't roll, solenoid MIGHT try to pull in (also could be bad ground related). Another way to check would be to hook a grounding starter cable from the battery neg to the starter housing.
Just a wild guess. Couple of Fords with the woven grounding strap drove me nuts for a while.
Fuddyduddy1952
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Do you have this meter? Curious because one review says: "The amp meter part has never worked and didn’t even know it until I needed it for the first time. Everything else is great but I got it for the amp clamp".
Maybe he got a defective one.
I use both analog and digital. I have this ammeter and it works, I'd rather see the analog movement than flashing numbers for this application.
That fused 60 amp circuit goes many places and my curiosity is what the current draw is with glow plugs disconnected. It's possible having a load then adding plugs blows fuse.
WinterDeere
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Yes, I have that exact meter, and it works well enough for the home user. The low-end drop out is higher than listed, it won't measure 340 mA Christmas light strings without making a few turns around the clamp, but Michael Faraday figured out the solution to that way back in the 1830's.
I had two vintage Amprobe meters, but my father's (AC / DC 1970's? vintage) was stolen by a contractor working in our house, and my grandfather's (AC only 1940's? vintage) reads about 20% low. I should take the time to figure out how to adjust or repair grandpa's, but there isn't a lot of information to be found for these on the web.
Agreed. Analog is definitely better for seeing anything quick... unless you have an o'scope.
I like zzvyb6's ungrounded starter theory. Seems a reasonable possibility.
hayden
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The fuse blows before the starter is activated, so it can’t be starter current. I’d guess one of the glow plugs shorts when there is current flow, so an intermittent problem in the plug.Yes, I have that exact meter, and it works well enough for the home user. The low-end drop out is higher than listed, it won't measure 340 mA Christmas light strings without making a few turns around the clamp, but Michael Faraday figured out the solution to that way back in the 1830's.
I had two vintage Amprobe meters, but my father's (AC / DC 1970's? vintage) was stolen by a contractor working in our house, and my grandfather's (AC only 1940's? vintage) reads about 20% low. I should take the time to figure out how to adjust or repair grandpa's, but there isn't a lot of information to be found for these on the web.
Agreed. Analog is definitely better for seeing anything quick... unless you have an o'scope.
I like zzvyb6's ungrounded starter theory. Seems a reasonable possibility.
If the plugs are out, you could try applying 12v to each individually to see how much current each draws. My guess is you will find one that shorts.
When you connect the glow plugs one at a time watch the tractor volt meter if one is not drawing enough current to blow the fuse but a partial short when that one is connected there will be a significant voltage drop.
Fuddyduddy1952
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I'm curious with glow plugs disconnected how much current does that 60A line draw? It could be not enough to blow fuse but glow plugs added in circuit blows fuse.
I have a large container of 12V incandescent bulbs. One is 450 watts so about 35 amps. Instead of blowing fuses I would clip that in place of fuse. If it is a bad glow plug bulb would glow bright when bad one is connected.
I have a large container of 12V incandescent bulbs. One is 450 watts so about 35 amps. Instead of blowing fuses I would clip that in place of fuse. If it is a bad glow plug bulb would glow bright when bad one is connected.
I have not had time to investigate yet but I like your idea. I may get to it tomorrow. Thanks.
ning
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Wouldn't it always be lit up?
The fuse has current running through it all the time, just doesn't blow unless it's too much current. Swap the headlight in there and you'll have current running through the light instead, not sure how this helps.
WinterDeere
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The intensity will vary according to the resistance of the glow plug. So if a glow plug is a typical 2 ohms, no matter what bulb you put in the loop, you'll never have more than 6A flowing off a 12V battery, through the series bulb/plug circuit.
But if a glow plug drops to 0.1 ohms due to an intermittent internal short, then up to 120 amps could flow in the circuit, depending on DC resistance of the bulb. Result: Bulb will glow much brighter.
In these numbers, I'm ignoring the resistance of the bulb itself, which is probably relatively low on a 12VDC circuit. I'm no lightbulb expert, but I suspect they have a very high PTC factor, resistance only goes up when they get hot. Measured with your ohmmeter, it might have a much lower resistance than it's rated wattage would have you expecting.
But those numbers don't matter here. Fuddy's idea works, as long as resistance of the bulb is not too much greater than that of the plugs, which is probably why he suggested a big honkin' 450-watter. The bigger the better, since a high bulb resistance (low wattage bulb) will make differences between two plugs much harder to detect.
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Fuddyduddy1952
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All I did for 43 years, and actually still do after 11 years retirement is troubleshoot electronic problems. I had to be creative. I never liked blowing fuses ($). A light inserted does two things: now it's a current limited circuit and a dead short lights the bulb. Of course the available current depends on the bulb itself...or parallel it with a shunt.
Of course a 60 amp circuit gets "tough" because now we're at 700-800 Watts depending on available battery voltage.
I prefer a circuit breaker, at least temporarily instead of fuse like this (Amazon of course) $10 one.
Try different things until it trips.
Of course a 60 amp circuit gets "tough" because now we're at 700-800 Watts depending on available battery voltage.
I prefer a circuit breaker, at least temporarily instead of fuse like this (Amazon of course) $10 one.
Try different things until it trips.
WinterDeere
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Yeah, I know you know your stuff, Fuddy! The guy I replaced at my prior job actually started life as a TV repairman in the 1950's, and his trouble-shooting skills as a result of that history were way better than mine.
But I just thought of one possible trouble with the lightbulb method, here. If the plug is only shorting out when it gets hot, you'll need to be sure your bulb allows enough current flow to get the plug to that state. A bulb rated 450 watts at 12VDC is going to limit the circuit to 37 amps or less, and when figured in series with a 1 ohm plug, you're looking at knocking plug current down something like 25%. That's probably fine when testing just one plug at a time, but you'd want a much larger bulb for testing them in groups.
But I just thought of one possible trouble with the lightbulb method, here. If the plug is only shorting out when it gets hot, you'll need to be sure your bulb allows enough current flow to get the plug to that state. A bulb rated 450 watts at 12VDC is going to limit the circuit to 37 amps or less, and when figured in series with a 1 ohm plug, you're looking at knocking plug current down something like 25%. That's probably fine when testing just one plug at a time, but you'd want a much larger bulb for testing them in groups.
MinnesotaEric
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I'm on the glowplug bus. Components can test okay with an ohm meter but once current is flowing through them, they can short out.
Think of this like a spark plug coil that allows the engine to start and idle, but it internally shorts out on acceleration of the engine because of increased power draw.
Think of this like a spark plug coil that allows the engine to start and idle, but it internally shorts out on acceleration of the engine because of increased power draw.
