Ford 1700 start aid quit working ?

[rayikeo2]

I have owened this tractor for 25 years. Durning cold weather I always use the start aid to pre heat before starting. It has always worked and started my tractor while out in the unheated shed. It coil quit glowing through the view hole when turning the Ign Switch counter clockwise and holding about 30 seconds. It worked (glowed) off and on for a while. My question is which part may be the cause: 1) The start aid coil, 2) The ignition switch, or something farther down the line to the cylinder heaters? How can I test this problem without replacing multiple parts? All you experts please give me some advise.

 

[JC-jetro]

I have owened this tractor for 25 years. Durning cold weather I always use the start aid to pre heat before starting. It has always worked and started my tractor while out in the unheated shed. It coil quit glowing through the view hole when turning the Ign Switch counter clockwise and holding about 30 seconds. It worked (glowed) off and on for a while. My question is which part may be the cause: 1) The start aid coil, 2) The ignition switch, or something farther down the line to the cylinder heaters? How can I test this problem without replacing multiple parts? All you experts please give me some advise.

Ray,

Get a test light or a voltmeter, check voltage or light when you glow-plugging. If you got no juice then you have a bad connection, broken wire or a bad switch. Before I change any components, I'd use a piece of wire and directly connect the glow plug to the battery positive terminal and then try to start to see if it starts. Glow plug is easy to take out, you can directly hook it up to the battery for few second and see if it gets warm or use a non-contact infra red heater to read the temp. do not do it more than 20 seconds for checking. The glow plug circuit is quite easy on 1700. just need to slowly eliminate the potential causes. Let us know if you need more details.

JC,

 

[Hooked_on_HP]

One thing to look close at is the glowplug indicator lite. It is not a lite. It is part of circuit. As voltage passes through the wire it gets hot and glows. Like JC says, get a test lite and start at the ign. switch and follow the wires to the glowplugs cheching at every connection.

 

[JC-jetro]

Below you can see the picture of the glow plug heater as Bill mentioned. The heater is in series with the plug carrying the juice and body ground completes the circuit. potentially if you preheat for too long the resistive wire may burn same as what happens to light bulb filament and opens the circuit. I'll check with the voltage there but jumping the termination contact should bypass the heater as well.

JC,

The whole gas tank comes off with two nuts and affords you plenty of room to fiddle with the wiring under the dash. Dash is on the right side of the gas tank.

 

[JB4310]

JC, Does the power go thru the Glow Indicator to the GP's and ground to engine, meaning that if the GI was open (burned out) the GP's would get no power? vis versa if the GI lights up then at least one GP is working completing the circuit to ground. or does the GI have it's own ground and glow independent of the plugs?
Why do both leads from the GI go to the switch (according to your schematic) term 17 and 19?

Ray, didn't mean to hijack your thread but my 1700 has been rough starting and I suspect maybe one glow plug is burned out. You didn't say whether your having trouble starting or just noticed the indicator not working.

 

[Hooked_on_HP]

The power goes through the indicater and grounds via the glowplugs. To check your glowplugs disconect the wire going to the glowplugs and the jumper from glowplug to glowplug. Take an ohmmeter and check from the center of the glowplug to ground. The resistance should be 1 ohm.
Bill

 

[Hooked_on_HP]

I was WRONG on on the ground for the indicator . It does go back through the ign. switch.
After further investigation I was not wrong. 12v comes from post 19 on the ign. switch goes through the glowplug indicator back to post 17 on the ign. switch where it connects with the wire going to the glowplugs . Post 17 does nothing. I wonder why they didn't just run the wire from the glowplugs to the indicator.

 

[JB4310]

The power goes through the indicater and grounds via the glowplugs. To check your glowplugs disconect the wire going to the glowplugs and the jumper from glowplug to glowplug. Take an ohmmeter and check from the center of the glowplug to ground. The resistance should be 1 ohm.
Bill

I do have a good dig multi meter but don't completely understand all its functions, Basically I understand how to read voltage and how to test for continuity. Since the GP is just a coil then if the wires are removed couldn't I just check for continuity from the term on the GP to ground? is the resistance of 1 ohm basically a measure of continuity?
I see that term 19 in JC's schematic looks like it could be a ground completing the indicator's circuit assuming that 17 is the hot feeding both the indicator and the GPs, is that normal to have a ground in a main ignition switch?

JB.

 

[RickB]

I was WRONG on on the ground for the indicator . It does go back through the ign. switch.
After further investigation I was not wrong. 12v comes from post 19 on the ign. switch goes through the glowplug indicator back to post 17 on the ign. switch where it connects with the wire going to the glowplugs . Post 17 does nothing. I wonder why they didn't just run the wire from the glowplugs to the indicator.

Post 17 supplies voltage directly to the glowplugs while cranking. The indicator coil is not powered while the start solenoid is engaged.

 

[Hooked_on_HP]

As usual Rick you are right. I just went out and checked and do have voltage on 17 while cranking.