303.5 glow plug operation?

[Matthew Eaton]

2008 303.5 glow plugs. What's makes them
Not work. The light comes on when the key is first turned like a test for all the dash. But it doesn't stay on and cycle the glow plugs. Starts slow.

 

[thepumpguysc]

Just because the lite comes on, doesn't mean they're actually coming on..
You'll have to get a test lite to SEE if your getting voltage TO the GP's.. IF YOU ARE.. take them out of the engine & put voltage to them one at a time to SEE if they are working..

 

[Matthew Eaton]

Thanks for the interest. I haven't gotten that far yet. I'm sure they aren't coming on. The light only comes on for a split second when i first turn the key. Like a check engine light on a car. It doesn't stay on for 10/20 seconds like a 303 rental I ran the other day. There isn't any power going through the 5a glow plug fuse. I'd like to dig in a little this weekend and see.

 

[kshansen]

Any chance of a complete S/N just on the chance there is a "systems operation" description that might explain how they work or at least a wiring diagram to point in the right direction.

Just for kicks I did look at one S/N Prefix DMY and there is at least a wiring diagram for that one on SIS and it shows both a timer and relay in the glow plug system.

 

[Matthew Eaton]

That would be nice to know what components there are and what wires are what. I'm usually pretty good with diagnostics. My serial # is DYM02176

 

[Matthew Eaton]

Oops. I do mean dmy02176

 

[kshansen]

Oops. I do mean dmy02176

Well see if this give you any hints on where to look:

 

[Matthew Eaton]

That is awesome. Thank you.

 

[kshansen]

That is awesome. Thank you.

Should I send an address for you to send the check?

Just kidding glad to be of some small help.

 

[thepumpguysc]

I cant remember who it was, but I helped someone out ONCE..[lol].
& they were in the Maple Syrup business & they sent me a bottle from their "farm".. MAN.. that was the best syrup I ever had,,
Awhile back we had a LONG thread about getting a Perkins started/fixed.. I "won" & told the guy to send me a "pot holder".. lol
I think it would be fun to get actual "pot holders" from around the country..?? but that's just me.. I use them daily & they don't cost squat..& easy to ship..

 

[Matthew Eaton]

Well the diagram was quite helpful. But I'm still not quite there. The glow plug timer checks out except for one thing. Grd is good B+ is good and key on + is there. The white wire sends power to the glow plug relay but it never quits. Anyway, not the main issuer since the glow plugs still don't work. They big yellow wire on the glow plug relay is dead. Tracing that back through the diagram is...different. I knew that the 5a fuse has no power, that's in the line there somewhere. Getting closer anyway.

 

[Matthew Eaton]

We just made some cider. Could send that around the country. But it doesn't really hold up long. Gotta keep it cold or shoulda canned some. That would preserve it.

 

[John C.]

Do the glow plugs turn on by themselves or do you have to turn the key switch to the heat setting? I'm asking because I saw one series of machines with the auto unit not turn on the plugs unless the ambient temperature was below somewhere around 45 degrees F. They were a pain because it then took a bunch of cranking to get the engine started. I think there was some sort of update for that but don't know for sure. Maybe someone here has the information.

 

[Matthew Eaton]

I don't have another key position. I think they are supposed to come on by themselves.

 

[kshansen]

Well the diagram was quite helpful. But I'm still not quite there. The glow plug timer checks out except for one thing. Grd is good B+ is good and key on + is there. The white wire sends power to the glow plug relay but it never quits. Anyway, not the main issuer since the glow plugs still don't work. They big yellow wire on the glow plug relay is dead. Tracing that back through the diagram is...different. I knew that the 5a fuse has no power, that's in the line there somewhere. Getting closer anyway.

Note: below the numbers in ( ) are the wire numbers on the drawing and if this is like most Cats the numbers are printed right on the wire, say every 4 inches.

What I'm seeing from here is the Yellow #10 wire(877) at the relay = the output voltage to the plugs. The red #10 wire(150) should be hot(battery voltage).

In the two conductor plug for the relay the white #18(323) wire is always hot(battery voltage) and the timer activated the relay by grounding the white #18 wire (L987)

So far have not seen anything indicating that there is a temp sensor in the system, need to look closer.

 

[Matthew Eaton]

That's where I was at. Looking like a bad relay. Nothing coming out of the yellow 877 wire. Could it be that simple.

 

[kshansen]

That's where I was at. Looking like a bad relay. Nothing coming out of the yellow 877 wire. Could it be that simple.

Does the white #18 wire (L987) show as going to ground when key is turned on? Or when key is in start position? Tried finding anything in SIS that explains the operation of the timer, so far no luck.

Just checked availability on that relay, Cat does think a lot of them! They are asking $88.53 for that little 12 volt relay, they do show stock in Syracuse and York PA among other places.

 

[Matthew Eaton]

Goes to ground in start position.

 

[kshansen]

Goes to ground in start position.

If it is going to ground in "start" does that activated the glow plugs? If not it is starting to look like the relay might be bad. Hard to be sure from here but ....

Don't suppose you could get a quick look at that rental to see what is hot with key on before cranking???

 

[Matthew Eaton]

I probably could. I just jumpered the white wire TJ ground. The real clicks and the yellow wire becomes hot. Relay must be alright. The key on circuit coming out of the timer isn't cycling. Only when cranking.