TC35D glow plugs sometimes don't come on.

[wolfie1959]

Sometimes my glow plugs don't come on. And sometimes they come on when it's running. I'm pretty sure the glow plugs themselves are ok because when the light does come on it will start right up.when the light doesn't come on I will have to jump it to get it to turn over fast enough to get it started. I don't know if it's the timer or the relay or both or maybe a loose or coroded wire... Where should I start to figure this out? The timer and relay are about $100 each so I'd rather not spend the money unless I'm sure I need to.

 

[Roadworthy]

Try tracking the problem down with a voltmeter or an indicator light. If it's the relay you can get a "brand X" for far less than $100.

 

[wolfie1959]

I'm not really sure where to start.. I'll see what I can find in the service manual. if it is the relay what would I look for that would work besides the one it calls for?

 

[dlctcg]

Wolfie1959 - I'm guessing it is the timer based on your description but a couple of things to check first.

- Check your connections for corrosion (the relay panels on the TC are a favorite spot for mice to build nests... they make a mess & cause corrosion; hopefully they are not the issue).... so if not check the following:
- Ignition Switch Connector; the factory switches are also known for going bad, but it doesn't sound like that is the issue based on your description.
- Glow Plug Relay Connections
- Glow Plug Timer Connection
- Check Fuse #1 - which controls the glow plugs & Fuse #2 - which controls the operator safety systems for corrosion....

If these all look good then it is easier to just try switching out the Glow Plug Timer Relay with one of the others, either the Headlight Relay or the Neutral Starter Relay (they are all the same - I usually use the headlight one).... This should let you know if the relay is the problem.... If so you can get an aftermarket one from a local Napa (much cheaper)... I don't remember the # but if you find that is the issue they can match it up (or let me know & I'll see if I can find it)... but I'm guessing this will not solve the problem....

My guess (& concern) is it is the timer.... the concern comes from your statement that "And sometimes they come on when it's running"... To me this is worse than them not working, as it will burn out the glow plugs prematurely if they are energized the entire time the machine is running (& quickly)....

I know somewhere on here there was a reference to an alternative part number that was substantially less but I wound up purchasing a NH #SBA385870301 (yes approx $100) because I didn't want risking saving $45 -$50 for a part on our tractor... but you can find them out there for under $50....

Attached are a couple of images showing the fuse & relay locations I mentioned above.... Hope this helps