M1009 Horn wiring and relay switch

[harryhr]

The horn on my 1985 M1009 decided to stop working a few days ago. When I press on the horn button all I hear is a clicking sound from under the dash. I checked the fuse and it's good. Did the horn relay switch go bad? I also noticed a
capacitor in the wiring just before the connection to the horn. I went over to the local chevy dealership (because in the past they serviced the local National Guard and Reserve unit's CUCV's) to ask if they had the parts on hand. The parts have been out of the system for quite some time. The local; auto parts stores don't have a clue. Any and all help would be much appreciated

 

[NovacaineFix]

Check your headlight fuse as well, the 30 amp, is it burnt around the fuse? I believe the horn is fed from this circuit as well, but If your hearing the clicking noise, that tells me that the horn relay is good, it may be just your actual horn is bad. If you can get to it, (it's behind the grille driver's side) disconnect the wire going to it and check to see if you are getting 12V there when the horn button is pressed. If you are, then take a small jumper wire and apply 12V + to the horn (the electrical tab), does it beep or horn? If not, then you need a horn. If it does, then you may just have an intermittent connection or a corroded connection at the horn

 

[harryhr]

Thank you for the reply. I used a test light on the wiring that connects to the capacitor and continues from the capacitor to the horn. Power going into capacitor but no power coming out of capacitor. I also ran a jumper wire from the battery closest to the firewall to the horn. I figure that wire being hot the horn should work (but it did not). So I connected the jumper wire to one side of the capacitor and plugged the other side to the horn. Still nothing. I cannot find that capacitor at any of the parts stores (even NAPA). I was told by the local Chevy dealer that he remembers there was a recall on the cucv's for horn problems and that the capacitor was added in the power line to the horn. I'm stumped as to what to do. I need to find where the horn relay is at so that if I replace the horn that I may need to replace the relay. Little problems like this drive me nuts. Looks like an easy fix till after I get started. If I replace the horn, it is definetly not going behind the grill.

 

[harryhr]

While on active duty, I had the opportunity to drive the cucv's and never experienced any of the problems I have had with my cucv. I was an MP at Tompkins Barracks Heidelberg, Germany. The M1009 was our main patrol vehicle. Our Blazers accumulated a lot of miles on them and none of them sustained long periods of down time. It was mostly regular daily maintenance. My personal Blazer had 32,000 miles on it when I acquired it a couple years ago. I've already replaced the starter, the flex plate, brakes all the way around, brake bolster pump, one alternator, and the starter relay. I've only put maybe 425 miles on it since I've owned it. Since it was released from the army, I am the first civilian owner.

 

[Warthog]

From our experiences here the capacitor is not required and also causes horn issues. Just remove it.

From your tests it sounds like the horn itself has died.

 

[harryhr]

Thank you for your reply. Much appreciated. I shall replace the horn but remount it under the hood somewhere along the inner fender and run wire from the connection behind the grille to the horn. I really don't want to create a disaster trying to remove the dead horn. A standard 12V horn should do the trick (I hope).
So as long as I have that clicking sound under the dash, the horn relay should be good, correct? Once again, thank you for your reply.

 

[NovacaineFix]

Yes, a standard 12v horn will work. You can buy one new or pick one from a boneyard for a few bucks. If you pick one from a yard, just make sure the bracket is attached and will allow it to mount where you want it, if not going back behind the grille area

 

[harryhr]

Thank you again for all the information. I have just one more question, nothing to do with the horn. The voltmeter on the dash stopped working after I had to replace the right hand alternator because it stopped charging. So, when I had to replace the starter relay, I also replaced the voltmeter relay but it did not make a difference. So I probably need to replace the voltmeter? I would appreciate your thought's on this. Thanks again. Harry

 

[cpf240]

Test it and see. There are two relays next to each other, perhaps the wrong one was replaced? Just be careful pulling out the meter, as it is hot with 24v at all times. Best to disconnect the batteries while pulling it, then reconnect for testing.

 

[harryhr]

Thank you for your insight and advise. Anything electrical, I usually do disconnect the batteries. The relay closest to the starter relay is the one I replaced. According to the under dash diagram, this is the Voltmeter relay. But you did give me some insight and I will replace the other relay as well. The government printing department has been known for making printing mistakes in their manuals and sending out revised changes to this effect. At least that will narrow it down if the voltmeter still does not work. I dread pulling the dash panel because it's such a pain in the butt.

 

[Warthog]

Issues with the voltmeter relay and be a couple of things. First is the very bottom 24v fuse. Second is the resistor on the back of the meter goes bad.

 

[Tinstar]

Installed two new acdelco horns ( A note and C note)
New relay
NOS horn parts in steering wheel and still no horn.

Turns out it was the turn signal switch inside the steering column.
All checked good with a multimeter but the horn contact button was shorting out in the right conditions.

Replaced old with a NOS switch and horn works.

Used it today.

Acdelco still makes the switch btw

 

[harryhr]

Thank you to everyone who gave me the heads up on my horn problem. The horn was dead. Installed new horn on the left had inner fender just in front of the windshield washer fluid container. Ran the wiring from behind the grille thru the body opening just below the headlight. Put in a "high" side load horn and it works great. Now the only thing left to do is pull the dash instrument panel and replace the 24 volt meter. I better disconnect the batteries before doing this (I take no chances with "hot" wiring.

 

[harryhr]

Hi Warthog. I'm going to tackle the voltmeter this week. You mentioned a 24v fuse....where? on the fuse box? Secondly I tried to find the 300 ohm resister for the voltmeter but no one has one (to include Radio Shack).

 

[Tinstar]

Install a 24v gauge and never worry about a resister ever again.

 

[harryhr]

I was thinking exactly what you wrote. I was thinking what difference would it make if I replaced the volt meter with a 24V gauge used in all the M series vehicles.
I was told by a couple CUCV owners that "oh no, you need to replace the volt meter with the same type". The voltmeter in the dash looks identical to the gauge I have in my M151A1. Thank you for the heads up.

 

[Tinstar]

I was thinking exactly what you wrote. I was thinking what difference would it make if I replaced the volt meter with a 24V gauge used in all the M series vehicles.
I was told by a couple CUCV owners that "oh no, you need to replace the volt meter with the same type". The voltmeter in the dash looks identical to the gauge I have in my M151A1. Thank you for the heads up.

The 24v voltmeters work perfectly.
You can use the military one or an aftermarket one like ISSPRO or VDO.
The only issue with the military version is lighting. You will have to do something to use existing bulb to light gauge and not the entire underneath of your dash.
Military ones are clear cased and use an external light source. The ones I've seen anyway.

Aftermarket ones have their own internal light bulb.
Either way, install and your done.
No resistor. No worry.

Why GM used a 12v VM when the power supplied is 24v is beyond me.

 

[cpf240]

...

Why GM used a 12v VM when the power supplied is 24v is beyond me.

And why did they decide to control the ground side of it with a relay, rather than the hot side?