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2021 Cat 289D3 no power to glow plugs!?!?

J

Johnkorpita

Member
Joined
Nov 15, 2023
Messages
15
Location
Colorado
2021 289D3 JX905845

Cold weather hit and it was struggling to start in cold. Started checking some things and there is no power to glow plugs. I recently got Cat ET to solve some other calibration problems on this machine....and so I and hooked it up...In ET, it shows that power to starting aid is ON when key is turned and glow plug light is activated on screen. I can't seem to figure out if there is a fuse or relay for the glow plug/starting aid. When I check incoming voltage to the wire that powers the glow plugs, there is no power incoming when activated. No fault codes.

Has anyone experienced this?
Anybody know if there is a fuse or relay somewhere?

Thanks for your help!
 
Deimos

Deimos

Well-Known Member
Joined
Nov 8, 2024
Messages
220
Location
RUS
I recommend checking relay 19A and fuses 15, 21, 32.
 

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J

Johnkorpita

Member
Joined
Nov 15, 2023
Messages
15
Location
Colorado
Deimos said:
I recommend checking relay 19A and fuses 15, 21, 32.
Click to expand...
Thanks so much guys! Nige, The schematic was extremely helpful and I traced it back to a blown fuse that feeds the relay to the glow plugs....thanks Deimos, that was the right spot you pointed out.

I bought a new relay because it was only $9 and installed that along with a new fuse. As soon as I cycled the glow plugs the fuse blew. I only got one fuse and it took 4 auto parts stores to find it....so I will grab more and do some testing to see where the short is coming from. I may have a glow plug that is bad. Do you guys know what OHMS the glow plugs should read if they are good? If I find that the wire isn't causing the short, am I right to assume a bad glow plug or two or 4?
 
J

Johnkorpita

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Joined
Nov 15, 2023
Messages
15
Location
Colorado
SOLVED: I wanted to give an update so if anyone else has this problem it may help. I had one glow plug that was bad, it was shorting out the fuse that feeds power to the relay that activates the glow plugs. I replaced the glow plug and everything is working. When I ohm checked the glow plugs, the bad one was lower than all the others by quite a bit. I also tested it by bypassing the suspected bad glow plug and only sending power to the other 3 glow plugs...no blown fuse when that happened so it was an obvious fix.
A Big thanks to Deimos and Nige for the help!
 
D

Drays259d3

Well-Known Member
Joined
Nov 15, 2024
Messages
45
Location
Auburn Illinois
Johnkorpita said:
SOLVED: I wanted to give an update so if anyone else has this problem it may help. I had one glow plug that was bad, it was shorting out the fuse that feeds power to the relay that activates the glow plugs. I replaced the glow plug and everything is working. When I ohm checked the glow plugs, the bad one was lower than all the others by quite a bit. I also tested it by bypassing the suspected bad glow plug and only sending power to the other 3 glow plugs...no blown fuse when that happened so it was an obvious fix.
A Big thanks to Deimos and Nige for the help!
Click to expand...
What did the good and bad plug ohm out to be? I tested Mine and they were all 2.1 ohms
 
J

Johnchodder

Member
Joined
Nov 7, 2025
Messages
6
Location
Mn
Drays259d3 said:
Hey! Go check out a thread I had On glow plugs. I explained how I was troubleshooting my problem.
Click to expand...
I did good stuff I removed the power strip and tested the glow plugs all had 1.4 ohms of resistance so I’m looking deeper I suspect it my be the relay or one of the temp sensors possibly the hydraulic oil thanks
 
Nige

Nige

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Jun 22, 2011
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38,517
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G..G..G..Granville.........!! Fetch your cloth.
FYI the glow plug activation (or not as the case may be) is most probably determined by the signal from the engine coolant temperature sensor.

Cold Start Operation​

The cold start aid feature assists with engine cranking during cooler ambient temperatures. Models equipped with C3.3B have glow plugs located in the cylinder head. Models equipped with C3.8 have an air induction heater located in the air inlet line. On models meeting Tier 4 final emission standards, actuation of either feature depends on the coolant temperature and is controlled by the Engine ECM. On the remaining models, actuation of the cold start aid depends on either the engine coolant temperature or hydraulic oil temperature. For these models, actuation of the cold start aid is controlled by the Machine ECM.

From your machine Serial Number I believe that your engine is a TIER 4 Final.
 
J

Johnchodder

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Joined
Nov 7, 2025
Messages
6
Location
Mn
So after diving deeper and blowing another 50 amp fuse tasted the wire harness for shorts and found none removed the power supply to the glow plugs and hooked up a battery charger it pegged and kicked out so tested the plugs removed individually and two of them short out under load new glow plugs another 50 amp fuse and seals are on the way
 
ThreeCW

ThreeCW

Senior Member
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Dec 15, 2019
Messages
275
Location
near Calgary, Alberta
Interesting that all glow plug tested at 1.4 ohms but 2 of them shorted under load. Good to know!

I assume that you are replacing all 4 glow plugs ... as failure of the 2 that tested well may not be far behind. Kind of sad that you are having to replace glow plugs on a 4 year old machine. How many hour are on it?
 
J

Johnchodder

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Nov 7, 2025
Messages
6
Location
Mn
Yes parts will be in the drop box in the morning from cat 4 glow plugs , 4 seals , 2 -50 amp (1 spare ) fuses and a new relay as well
 
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