i have been tinkering with a 6.2, is it absolutely necessary to have the glow plugs working for the truck to start, even though it has been 75 degrees and hotter outside?? if so, how do i test the system, or a way to heat them up the hard way, i need to get this truck running, my suburban now needs an engine, this 82 is my last resort... HHEELLLPPPPP!!!!!

Check voltage on 1 side of glow plug relay, always should be there. Then turn the ignition on and you should hear a click, if not check wiring to relay, if so then check other side of relay going to the plugs, if voltage then relay is good. Check resistance on each seperate glow plug. They should be similar to each other. Also check voltage at each glow plug, the relay should toggle on its own so this would be fun.

to fire up that engine, just to get it run, disconnect the batt to glow controller connection [ A MUST] and use some starter fluid[ be carefull with that] That is how I start my Waldon [see sig] cause there is room on it for only 1 batt,and glowers drain to much juice for start.

do search for glow system check.

If you are not sure about the location of the controller or connector, then just disconnect the small diameter wire from the glow plug relay on the driver side fender before using the starting fluid....and don't get carried away with it....all it needs is a short squirt.
The glow plugs are necessary for normal operation of the engine and using starting fluid is a last resort of desparation. Continued use of starting fluid to start it is ill advised. For the engine to start without glow plugs or starting fluid would require the engine temp to be over 100 deg. F and even then it will take some cranking if its under about 130 to get'r going.
Regardless of whether you intend to drive that vehicle or transplant that engine into the other...the glow plug system will have to be diagnosed and repaired.
Glow plug resistance has to be under 8 ohms, preferably under 5 ohms for them to work. They also require a great deal of amperage, a voltage test may not necassarilly be enough. The contacts in the relay itself can become burnt and corroded which increases the resistance thru the relay which will in turn drop the amount of amperage available to the glow plugs. Check the resistance of each and every glow plug, if within specs put a voltage meter on a battery (power and ground). Make a note of the voltage (should be at least 12V), run a jumper or remote starter switch from the positive post of the battery to the small stud on the glow plug relay (the relay control post). Do not energize relay for more than 10 seconds. With relay energized, check battery voltage again. If system is functioning properly you will see 1.5 to 2V less than the previous check. If there is no drop in voltage then there is an open in the circuit which would be either all glow plugs burnt, fusible link blown, or faulty glow plug relay.

k wat i do every morning is snap tha #1 glowplug wire off..than run a wire from tha glowplug wire to tha positive off a battery charger than ground tha charger and turn it on (Charge) ,not ur battery unless ur stuck sum1 cause it will drain them, than walk back to tha cab and the CHECK ENGINE light will be on than try to start it once it starts disconnect tha wire to tha charger or u will ovr heat tha plugs

You have a battery charger that puts out 55 amps?

no im only pushin 2 amps but it seems to work real well..sumtimes i go to 10 but on 2 i just sit and wait for tha glowplug light to shut off tha crank it and it fires rite up

Hmm. What voltage do you see on the batteries, the glow plugs and on the fuel shutoff solenoid when glowing with and without the external power supply?

im reading normal 13 voltage

im reading normal 13 voltage
Then you have a prob with glow solenoid, fusible link, or glow controller.

if i remeber rite its tha contoller

It should start without glow plugs at 75F. The glow plug light should not go out with (external) voltage fed through a glow plug wire. The glow plugs won't exactly get hot with only 2 or 10amps provided. Nominal voltage is available at the glow plugs and the fuel shutoff solenoid in any case, and it still doesn't start --- but it does start with the external voltage supply.

This doesn't make sense to me ...

I got the impression that he did not have voltage to the glowers without the external source. I suspect his voltage reading was taken from the battery itself, and not from the glowers connector.

ya i dont get juice to tha plugs in tha mornin so i just heat 'em up with tha charger fire tha truck up and let it idle for a min or two and fires up all day

Ok, that should be easy to fix. Check the voltage on both sides of the glow plug relay, unless they are very different from later setups, there should be 12V on one side all the time, 12V on the other side (switched on by the relay) while the glow plugs are glowing.

Don't forget that if you have a controller prob, its possible that it is not powering the control circuit of the glow relay, and that there are 2 fusible links between the relay and your glow plugs (they should both be within a few inches sight of the glow relay)

i rember doin tat already i get voltage on tha battery side of tha relay but not on tha other side so i went and bought a new one and its still not working

i rember doin tat already i get voltage on tha battery side of tha relay but not on tha other side so i went and bought a new one and its still not working
bought a new what, relay or controller? If you didn't get voltage on the glow plug side of the relay that doesn't necessarily mean that the relay is bad. Its more likely that the relay controller isn't energizing the relay.

i got a new realy srry and i was reading my 6.2l diesel book and it said somthing tat an alternator wire could be tha problem brb ill go get it

its says somthing like a DIODE fails in tha alternator

its says somthing like a DIODE fails in tha alternator
K, close the book for now....Use a jumper from the positive post of the battery to the small lug on the glow plug relay (do not leave it on for more than 8 seconds), listen for an audible click and check both large lugs for battery voltage with jumper hooked up (have meter ready so you don't end up having relay energized for more than 8 seconds). Let us know what happens after you do this.:thumb:

it clicks without tha jump tho or still try it?

K, don't use the jumper then. Do you have voltage on both of the big lugs with the relay energized? If yes, check for voltage at the glow plugs,...both sides of the engine.

yea tats tha problem it clicks but not voltage on tha rite side of tha relay

Do you have voltage at at least one of the sides of the relay while the relay is energized?

I'm asking because a new relay that clicks should be working fine, so maybe the supply side of the relay cuts out for some reason when there is a load on it. Measuring voltage with a voltmeter only doesn't create much of a load, so you could see 12V on one side and it still doesn't work. --- This isn't likely, but possible ...

K, leave the key off. Use the jumper on the relay (no more than 8 seconds), check the voltage on both large lugs of the relay with the jumper hooked to the positive of the battery and the small lug on the relay. Let us know what you get.
I see what you are saying Lee and I would think that the relay would be working too. Assuming it is working, if the circuit is loaded enough to drop the circuit voltage on one side, then it would also drop the other side, as it is the same circuit.

Have a 1982 GMC Suburban C1500/ 6.2L V8 and the 'glow plug switch' has gone out on me. Its my only car at this time and I need to get around. Is there a way to get the truck started by either bypassing the switch or some other way that will possibly not damage the engine. I read that a quick blast of starting fluid would get it to crank but I have also SEEN what happens to a diesel if used too much. I am in the army and some trucks are mounted with a "Cold Start" switch, and its not pretty. But I dont have much options, I dont exactally have the $145 to drop on the part right now. Would love the help.

84 GMC 6.2L J K2500 . Found only 10v at the coil power plug for the solenoid without plugging it into the solenoid. Found around 12.5 everywhere else. Replaced the screw into block controller. Still only 10v to coil. The plug that plugs into the coil is as best as I can tell factory. It has what seems to be a diode crimped into the connections between the wire and the pins inserted into the black plug. Checked it with a meter and it shows failed. Cut it out. Voltage is now back up. The solenoid fires and everything seems good. Now I don't know why GM saw fit to install the part across the pins on that plug, but if someone else can explain then I would like to know.