well 3 7 second glows and it did not work. i know they are getting power and they must be glowing. im about to install an either system.
You know they are getting power, how can you tell? Did you take one out, ground the body out and leave the wire attached to the end and see if it gets hot? Unless you have no compression, I can
guarantee they are not getting powered on properly.
If everything was working properly then it would have started on the first 7 second try. Did your painless harness replace anything under the hood, such as the two big power wires that feed the relay for the glow plugs? Often times the connector that separates this pair is melted, burnt, and corroded to hell and not transferring enough juice...
These glow plug systems are very simple really... like this:
- Batteries to the glow plug relay power-terminal (the power wire is usually wired to the starter relay power input instead of directly to the battery positive)
- glow plug relay has 4 posts generally: 2 big posts for power IN and OUT. IN always has power, out only has power when you tell it to, this is what makes the glow plugs get power to get hot. 2 small terminals are for grounding and for Signaling the relay to come on using a positive charge
- So with a big fat hot wire going to the relay power input terminal there are two ways to manually turn the relay on: control either the ground or the Signal terminal. The cleanest way to control it is by using the ground terminal as you only need to run one wire into the cab.
Option A:
Take a small bit of wire and crimp on a fat ring terminal connector on one end and a small one on the other, install the big end on the Power Input terminal with the big hot wire from the battery+ source, the other end goes on the Signal post. Without ground the relay remains off. Some relays are externally grounded through the relay body - if you hear a click on when it is mounted then there is a good chance it is. This means this method wont work. The stock ones are not, thus the need for a ground terminal. Run a wire with a small ring terminal from the ground terminal into the cab to a button. Run another wire from the button to anything/anywhere grounded - you can do this in the cab and not have another wire going out. This keeps the system simpler and now you don't have to have two potentially hot wires passing through the firewall.
Option B:
Run a grounded wire from under the cab to the ground terminal of the glow plug relay. Run a wire from the Signal terminal to a button in the cab, run another wire with a fuse and holder from a battery+ source to the button in the cab.
Bonus: either system you can hook up two debug LEDs easily: run a wire from the glowplug relay output terminal to inside the cab, hook it up to an LED+resistor or 12v lamp and then ground the other side and you can tell when the relay is on and glowplugs should be getting power . If the light isn't on then it is either burnt out, wire is damaged, relay is shot, or your button is not working. The relay will still turn on even if all 8 glowplugs are dead. If the light stays on then you either have a bad button that is sticking, a relay sticking, or some similar issue. If you act quick you could potentially save the glowplugs from death caused by a stuck relay.
- Lastly hook the glow plug harness up to the output ring terminal. It is a good idea to take the covers off of the harness to make sure it isn't falling apart anywhere, several of these old trucks I have worked on had wires broken off, one had 3/4 broken off all together on one side but you couldn't see it and the manual glow plug system acted like everything was fine.
Diagnostics
Easy way to test if this is a possible culprit, take a heavy duty wire like from a starter or at least a battery cable, hook it up to the glow plug-side of the relay, then to the positive of a battery. THERE WILL BE SPARKS. Use care. This is bypassing all of that other crap, everything except the glow plug harness and glow plugs themselves. Count to 7 again. If it starts, yay - everything after this point is fine, the problem is at this point or before.
Check those two wires I talked about, they are brown nearer to the batteries and yellow nearer to the relay, split by a big fat gray connector. Look OK? Replace the relay. Even if it is new, it could be defective. Another test you could do here is take something you don't mind getting chewed up like an old thick screwdriver and fitting it between the two big posts on the relay and then turning it into both of them so it doesn't bounce around and arcs the two contacts. THERE WILL BE SPARKS, use care. Count to 7, then remove the screwdriver or implement carefully. Don't get shocked. Whatever you use will get some arc-burns and damage so don't ruin a fancy snap-on tool ;p. If it starts up, the relay is the culprit - either corroded terminals/wiring or it itself is crap.
Be careful, not my fault if anything happens
and good luck. There really isn't that many places to check.