Gen 2 problems

[DerangedMadman]

I have had my M1008 for a few months now and I absolutely love it. Since I have had the truck the Gen 2 light has never come on at all. After reading many posts on here I have learned that it must so I have searched it and did all of my reading up on what it could be. Unfortunately I am still lost and trying to read through all 940 pages of the -20 is something I don't think I have the patience for so I hope you can help.

I thought it might be the bulb so I pulled it out and it looked good. I then took a test light and checked the copper strip where the bulb socket is. There I have 24VDC. I went to the auto parts store and bought a brand new bulb just to be on the safe side but still nothing.

I guess my question is on the back panel where the bulb socket twists in, is the other side a basic ground or is it a closed circuit? I was guessing it had to be a closed circuit if it is to be part of the charging system but I am not sure. If it is a closed circuit where does that circuit go to so I know where to look for the problem? Does it run back to the Alt on the passenger side?

I just bought an volt meter and ohm meter to help me figure it out but unfortunately it is way too dark tonight to mess with it. Any help on leads of where to start would be great.

Thanks,

 

[Warthog]

The bulb is part of the Gen circuit. It doesn't have a ground until it gets to the alternator.

Check for 24v at the two pin plug on the passenger alternator - Gen2. The red wire should have 24v at all times. The brown wire should have 24v when the key is on. Clean the plug while you are at it.

If that doesn't fix it, there is the relay and the diode to check.

http://www.steelsoldiers.com/cucv/50551-cucv-switches-diodes-relays.html?highlight=diodes

The path of the circuit is:
24v from the fuse box to the Gen2 bulb
from the gen2 bulb to the gen2 relay
the relay is energized when the key is on
gen2 relay to gen2 diode
gen2 diode thru a connector
connector to the alternator

everything in the circuit must be working for the alternator to excite and produce power

Right click on thumbnail and choose "Open Link in New Window"

 

[DerangedMadman]

Thank you this should help a lot. I appreciate it.

 

[DerangedMadman]

Warthog,

Once more question, The glow plug light in the dash is not getting any power. It hasn't since I have had it. The glow plugs are working correctly though as I can hear it click off in about 20 seconds after I turn the key on when it is cold and the truck fires right up. I just want to make sure there is no way that the Gen 2 light and this light have nothing in common. This light will be my next fix.

 

[Crash_AF]

I'm assuming you have checked the bulb to make sure it's not blown? The GP light gets its power directly from the pink/black wire which is a common power supply wire when the ignition is in the RUN position and powers many different circuits.

The ground for the light runs to the glow plug controller box on the dark blue wire.

Later,
Joe

 

[Warthog]

yeah, what he said....................

Crash know these truck inside and out. He knows his stuff.

Have you download all the tech manuals? There are great troubleshooting sections in them.

 

[DerangedMadman]

Okay,

It looks like the original Alt. The numbers on Gen 2 is 110550/100 Amp/6F20/12V and the numbers on Gen 1 is 110550/100 amp/6C12/12V. I have 25.6 volts on the red wire. The brown wire does not get to 24v even with the key on. Would this be the relay or the diode? The Gen 2 light has not come on at all so how can I still have over 24 volts at the battery if this has not been charging at all months?

 

[DerangedMadman]

Is there a way to test the diode or relay?

 

[DerangedMadman]

Okay,

I have 24 volts going into the relay on the Brown and red wire. There are 2 brown wires and a pink wire running out of the relay. They go into a harness up towards the top of the dash. On that Harness I found a diode (sits behind the voltmeter). On one side of that diode there is no voltage and the other side has 14.5 volts. Is that voltage backfeeding from the alt? Seems like there is a breakdown in the relay I am guessing. Does this sound right?

 

[Warthog]

Now it comes down to tracing the circuit.

You can remove the mounting bracket for the Starter Relay, Volt Meter Relay and the Gen2 relay. Or you can remove the black instument cover.

Pull out the Gen2 relay and check for 24v at I believe is the top plugin.

If not then the circuit from the instrument cluster to the relay is bad. Many people have had to remove the cluster and clean/fix all the contacts for the bulbs and the pigtail plugin.

http://www.steelsoldiers.com/electrical/43351-cucv-instrument-cluster-repair.html?highlight=cluster

http://www.steelsoldiers.com/cucv/46054-cucv-instrument-cluster-decoded.html?highlight=cluster

If that doesn't fix it then trace the circuit from the relay plugin to the alternator.

You can take a long wire and make a jumper from the brown wire at the alternator and use the ohm meter to check the circuit. If it doesn't show a closed circuit the first time, reverse the probes and check again.

If the circuit is bad you will need to remove the wade of duct tape at the diode and check the circuit there.

Keep us posted

 

[DerangedMadman]

I am wondering about the Pink wire running into the relay. All the other pink wires on the truck seem to be hot ignitions wires. Other than the 24 volt wire that is good feeding the relay from the instrument cluster, should there be any other hot wires going to the relay?

This may be the problem I am having with my Glow Plug light and Water in Fuel light as well.

Crash said earlier that those pink wires are standard ignition hot wires but they have absolutely no power running to either of those lights through the ignition. Could all of these be on the same circuit? I have checked every fuse and they are all good.

Does the relay need the ignition source to start it working?

 

[DerangedMadman]

Update. I went through the TM that you sent me and traced it back to E-4 on the side of the page. That is supposed to be a hot ignition wire. I went ahead and made a jumper and ran a hot wire to the relay and it began working. Not only did the Gen 2 light begin working but also the Glow Plug light and the Water in Fuel light are both working now. I have a missing link somewhere in the ignition wire that feeds all of those. Only question now is to try to track it down of just jump it.

I really appreciate your help on this. I would not have found it if you would have not posted that diagram.

Thanks again.

 

[Warthog]

Man, you didn't say the volt meter, gen2, transmission downshift, water-in-fuel lihgt and the wait light whern't working....LOL

Check fuse #15 in the fuse box diagram. Remove it clean it and the socket..

While you are at it clean the whole fusebox. (disconnect the batteries first...)

You may think I an a genius, (I did stay at a Holiday Inn Express once) but I have all these diagrams stored on my work computer.

After this you will check the fuse with the key on. If you don't have power you will check the ignition switch. They are known to gum up after 25 years and are cheap to replace. Less that $10 at Autozone.

 

[Crash_AF]

Yea, I just got home and saw this... if all of those systems are out it's probably fuse 15 or the fuse holder for fuse 15.

BTW, common in electrical terms doesn't always mean 'standard'. Common means that several components share a circuit (they have this power or ground in common).

When you jumped the circuit to test it, it 'backfed' (provided power to) the entire rest of the circuit which caused all of the previously unpowered components to come on.

Later,
Joe

 

[DerangedMadman]

LOL, Number 15 did not have a fuse in it at all. I guess that changes things a little. The decscriptions are not real readable on the fuse box. But this poses another problem all together.

I went ahead and jumped it to an ignition wire and EVERYTHING is working properly.

Just for ****s and giggles I put a 20 amp fuse in the fuse box and took it for a test drive. Everything worked as it should have until I got home. I went to shut the truck off and the motor continued to run. All the power to everything else shut off except the engine. I thought it might be the jumper I made but I am 100% sure it is an ignition wire. Now what?

 

[DerangedMadman]

Possible the ignition switch is bad or would something else cause the engine to keep running when you turn the key off?

 

[Warthog]

Read the Troubleshooting Section of the -20 manual. Paragraph 31, Page 2-27

"check the ground wire on top of the parking brake"

If you will right click on the thumbnail and choose "Open Link in New Window" the fuse box layout will be readable. Or you can look in the Tech Manual Section 4-12, page 4-31.

 

[DerangedMadman]

Is this the Ground Wire you are talking about. It is the only one I see and it runs into the main harness. It seems to be in great shape.

 

[1stSarge]

Yup

Yeah, that’s the one he means…some of them are on the parking brake bracket and some are on the bulkhead like yours…..following this closely as I have some similar problems, and still haven’t killed them all yet..

 

[Crash_AF]

Did you remove the jumper wire while you were test driving the truck? Remove the jumper wire if you haven't and see if the problem goes away. It is very difficult to accurately diagnose problems if there are bypasses in place because power can feed in weird ways through the system due to interconnectivity.

Later,
Joe