All lights

[Birddoghunter]

I changed the light switch assembly and everything was fine.
I had the m998 transported from Jupiter Fl to Ellijay ga. After it arrived I had no lights anywhere in the vehicle.
Question
Is there a main fuse/ breaker that I cannot find or know about.
I did add a grounding long before it was transported
Any help would be appreciated


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[TOBASH]

Perhaps your transporter had something to do with this issue?

 

[papakb]

When you post something like this it will help us help you by including the year and model of your truck. In the section above "if you need it it's here" you can download the schematics for the truck in TM 9 2320-280-20-3. They're in the back of the TM. These trucks are 98% the same electrically so almost any one of them will help you troubleshoot.

If you include things like what else isn't working it gives us more to go on to help you. Horn? Turn signals? Wipers?

There are only 2 circuit breakers behind the dash that protect all the elecctrical systems. CB1 is for the heater and CB2 is for everything else.

 

[Birddoghunter]

Sorry about lack of information
1989 m998
No turn signals
No head lights
No dash lights
No blackouts
No brake lights


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[Birddoghunter]

It runs and drives fine


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[osteo16]

It runs and drives fine


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"Fuse" behind instrument cluster??? Wish I could remember what its called., maybe someone will chime in before i dig it up..

 

[Milcommoguy]

And did it ever work in your presents?

Newbes need to get the TM's and follow along. I am not calling out any one personally.... BUT come on guys... it could be this or that or maybe this and ....arouund and round we we go with electrical problem.

Owning a HMMWV is not just a driving experience... it is a BIG learning experience. The TM (at least the schematic are going to be necessary to figure / follow thur most electrical problems, till one gets a feel for the "lay of the land".

I get it that the hobbyist are not taking it to the dealer. Well, some might. Poking and fiddling might work too if one is lucky.

It's not a slot machine... BUT having a understanding will make one a winner.

Nut and bolts most can see... messing with the electrical, going to need the "road map" and a simple tester IMO.

OK, not trying to be a big BUTT, take the fun out of it POOPer.......... and here's my guesses.

And no horn ?? Is the plug to the lighting switch seated correctly ? Lighting circuits have a circuit breaker built into the switch. Independent of any other circuit. No fuses to blow. The other switch, is it good?

Do any of the lights flicker or look to come on and go off very quickly? Something shorted tripping internal breaker. Might be hard to see.

On the connector PIN "F" is input power 28 Volts. With all those failed lighting circuits PIN "F" cable end would be the first test. It should be there at all times. It's a GO-NO GO and if a NO... Could be a pin on the PBC-EESS box or a internal fail. 24 volts flows straight right thru it to the lighting switch with no treatment. Could be ?? a cut wire / bent pin. Work it out using the schematic. Eyes open for anything unusual.

Any add-on, non factory modification all bets are off.

That's my free on line guess with a smile. That's how it can go with electrical. YRMV

There is a logic to my guesses, CAMO

 

[Birddoghunter]

I changed the light switch assembly and everything was fine.
I had the m998 transported from Jupiter Fl to Ellijay ga. After it arrived I had no lights anywhere in the vehicle.
Question
Is there a main fuse/ breaker that I cannot find or know about.
I did add a grounding long before it was transported
Any help would be appreciated


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Thanks for the good information and tips on the light problem on my m998.
Following the troubleshooting manual I got the cannon plug off behind the master light switch. I located pin F and found that there was no power at pin F. There solution was to repair or replace that harness. They are very vague on where the power to pin F originate. The manual states that it travels straight thru the protection box to pin F. Any information would be appreciated
Thanks


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[papakb]

The TM you want to look at is TM 9 2320-280-20-3. In the back of the manual are the schematics for the HMMWV. There are a couple different ones but the lighting circuitry is the same throughout the series so any schematic should do to troubleshoot your lighting issues. They're large drawings so your going to have to magnify them and then move around to trace the circuit your looking into.

Years ago I took the basic M998 schematic down to a local copy shop and had it copied double sized and then laminated so that I could draw on it with a grease pencil as I did me troubleshooting and then erase it for the next time.

The power on pin F of the master light switch comes from Pin F on the body connector on the control box which gets its power internally from pin E on the control box engine connector. Pin E gets its power directly from the starter motor on a large 8 gauge wire to provide battery power to the system.

Before you start disconnecting things to measure power remember that anytime you connect or disconnect the control box you want to have the batteries disconnected. You can reconnect them after removing the connector you want to test but connecting and disconnecting the control box connectors with the batteries connected is asking for trouble. Spelled $$$$$$$!

 

[Birddoghunter]

The TM you want to look at is TM 9 2320-280-20-3. In the back of the manual are the schematics for the HMMWV. There are a couple different ones but the lighting circuitry is the same throughout the series so any schematic should do to troubleshoot your lighting issues. They're large drawings so your going to have to magnify them and then move around to trace the circuit your looking into.

Years ago I took the basic M998 schematic down to a local copy shop and had it copied double sized and then laminated so that I could draw on it with a grease pencil as I did me troubleshooting and then erase it for the next time.

The power on pin F of the master light switch comes from Pin F on the body connector on the control box which gets its power internally from pin E on the control box engine connector. Pin E gets its power directly from the starter motor on a large 8 gauge wire to provide battery power to the system.

Before you start disconnecting things to measure power remember that anytime you connect or disconnect the control box you want to have the batteries disconnected. You can reconnect them after removing the connector you want to test but connecting and disconnecting the control box connectors with the batteries connected is asking for trouble. Spelled $$$$$$$!

Oh thanks for the help I’ll look it up and start tracing I bought an extra control box just in case but I do disconnect Oh the batteries


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[Birddoghunter]

Oh thanks for the help I’ll look it up and start tracing I bought an extra control box just in case but I do disconnect Oh the batteries


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Thanks for the past information very helpful. I finally got the correct TM followed pin F to pin E on the control box. It seems that there is no power on pin E. It seems that everything else works fine starts runs fine Gauges work. Would it be to stupid to send power directly from the starter where pin E recieves it power directly to pin F on the main plug on the master light switch. I would fuse that system separately.
Thank you
Roy Briggs
s asking for trouble. Spelled $$$$$$$!

 

[Birddoghunter]

Ok thanks


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[Milcommoguy]

It does pass thru the "BOX" . Battery HOT all the time. Inputs "BOX" on engine connector pin E. Thur "BOX" and out on body connector pin F. Over to the lighting switch to pin F.

Disconnect batteries before poking around. Have seen many burnt off "F" pins on "BOXes" when pokers miss the mark.

When your're hot, your're HOT, CAMO

 

[Birddoghunter]

Thanks for advice
I followed the schematic from pin F thru the box out pin 5 and back to the starter # 8 lug.
I have power at pin 5 going into the box. I have continuity through the box out to Pin F I don’t know if the continuity guarantees voltage thru the box.
I’ve got another box that I got I’m looking thru the TM to locate proper way to verify the boxes are good.
I’m going to call Mac Motors Monday maybe they can help with the box verification.
Any suggestions will be greatly appreciated
Thank you


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[TOBASH]

IIRC turning lights off before turning ignition off can damage vehicles. Also the switches have multiple positions that can confuse you. I have wondered why lights did not come on just to find I had the switch in blackout position.

I have a rough schematic of plugs and PCB box you might want to look at to help with understanding wiring.

check Post 51

How to bypass PCB? I am aware some HMMWV owners have done it.

good to know, I have fixed my location... Then why is your IP resolving to a different state?

www.steelsoldiers.com

 

[Birddoghunter]

It does pass thru the "BOX" . Battery HOT all the time. Inputs "BOX" on engine connector pin E. Thur "BOX" and out on body connector pin F. Over to the lighting switch to pin F.

Disconnect batteries before poking around. Have seen many burnt off "F" pins on "BOXes" when pokers miss the mark.

When your're hot, your're HOT, CAMO

IIRC turning lights off before turning ignition off can damage vehicles. Also the switches have multiple positions that can confuse you. I have wondered why lights did not come on just to find I had the switch in blackout position.

I have a rough schematic of plugs and PCB box you might want to look at to help with understanding wiring.

check Post 51

How to bypass PCB? I am aware some HMMWV owners have done it.

good to know, I have fixed my location... Then why is your IP resolving to a different state?

www.steelsoldiers.com

I have the box out and in my hand. I have continuity between pin 5 and pin F. Does that mean that it good or should I apply power to pin5 and check pin F for 24 volts before I go thou the gymnastics of reinstalling the box to its proper position and hooking power to the box for there. I can check it at the engine under the hood please advise


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[TOBASH]

I would NEVER apply voltage to a box out of the vehicle. Not unless it is a manual home made box.

My diagrams were more meant to show what circuits are where. I used these diagrams to build a manual box.

If that green box is your only box, you might want to be careful with it. I have opened Green boxes and repaired them, and I now have several, BUT because I have a manual box I am no longer worried about box failure.

Of course a poorly constructed manual box can and will burn out your truck an even burn down your house.