Drivers side door ajar short

[Mark F.]

Re: Drivers side door ajar short

I will check. Thank you for all of your help.

[Patrick H.]

Re: Drivers side door ajar short

Probably not. It has to go through a relay or it'll trigger the alarm any time you put courtesy Lights on via door buttons or headlight switch.

Check AIM for RPO xxx Alarm maybe?

In 1972 the alarm was standard, and no longer an option as it was in 1968-71.
So, you won't find it in the option section of the 1972 AIM.
It would, of course, be called out in the 1971 AIM if you want to see the pieces of it more specifically.

[Mark F.]

[Owen L.]

Re: Drivers side door ajar short

Try this wiring diagram from Willcox - the door ajar is in the "rear" section, lower right. It appears the white wire goes to the hood open switch.

Corvette 1972 wiring 2=.jpg

[Terry M.]

Re: Drivers side door ajar short

Hi Mark, Last night I looked at the schematic but couldn't find reference to the alarm. Then had to get some sleep.

Was that a option in 1972? If so, maybe the Service Manual has it.

But iirc, isn't the ajar switch 3 terminal? I repaired one on a '69 about 5 years ago but forget what went where.

Rich
P.S. Still on the road, in SC/GA border for a pee break and a coffee replenishment, and saw your post. If no one gets in here to help, I'll dig into the books when I get home tonight.

Rich
Door ajar light was standard beginning in 1968. The alarm system was also standard in 1972. There are probably connections from that switch to the alarm system. That switch probably served both door ajar and alarm functions.

Those switches usually have 12v going to them and they get a ground when they close. Those of us who grew up with AC find that method of operating "features" abhorrent. Folks who live in a DC world just think differently. Of course 12v DC is not as lethal as 120v AC

[Richard M.]

Re: Drivers side door ajar short

Terry, thanks for that info. As you know I'm a little deficient on the shark cars. But for electric..... I'm eager to learn the nuances.

Owen, That's a great diagram. Only problem is when it downloaded here it reduced clarity so you can't read details.

Would you please email it to me? I'll crop that section and the alarm wiring to repost with details. I'll drop you a PM.

Mark, I just looked at my 1969 AIM. UA6 is the RPO for the Alarm option for that year. I can scan the pages if you need them, but since the alarm is standard on your car, your 1972 AIM should(I'd hope) have the same pages somewhere in there(with any applicable updates) in Section 12 - Electrical. Maybe check again.

And it does show a relay, mounted on a shelf bracket riveted to the floor of the jack stowage compartment. Also a flasher so when it's activated it powers the horn on/off/on/off(beep...beep...beep).

In the '69 AIM, it shows the wires(not the color, I'll assume white), going to the door jamb switches(not ajar switches at the latch pillar) on each side. Those door jamb types are the ones at the hinge pillar screwed into the metal. Since the switch gets its ground via the threads themselves into the birdcage, it appears to have 2 terminals on each switch. One for the courtesy lamps, the other for the alarm "white" wires. I'm not 100% certain I got it right, maybe only 99.9%. lol

The wiring diagram in section 12 should show wire color details as well, but Chevy didn't always have that info as one would expect.

Rich

[Terry M.]

Re: Drivers side door ajar short

Terry, thanks for that info. As you know I'm a little deficient on the shark cars. But for electric..... I'm eager to learn the nuances.

Owen, That's a great diagram. Only problem is when it downloaded here it reduced clarity so you can't read details.

Would you please email it to me? I'll crop that section and the alarm wiring to repost with details. I'll drop you a PM.

Mark, I just looked at my 1969 AIM. UA6 is the RPO for the Alarm option for that year. I can scan the pages if you need them, but since the alarm is standard on your car, your 1972 AIM should(I'd hope) have the same pages somewhere in there(with any applicable updates) in Section 12 - Electrical. Maybe check again.

And it does show a relay, mounted on a shelf bracket riveted to the floor of the jack stowage compartment. Also a flasher so when it's activated it powers the horn on/off/on/off(beep...beep...beep).

In the '69 AIM, it shows the wires(not the color, I'll assume white), going to the door jamb switches(not ajar switches at the latch pillar) on each side. Those door jamb types are the ones at the hinge pillar screwed into the metal. Since the switch gets its ground via the threads themselves into the birdcage, it appears to have 2 terminals on each switch. One for the courtesy lamps, the other for the alarm "white" wires. I'm not 100% certain I got it right, maybe only 99.9%. lol

The wiring diagram in section 12 should show wire color details as well, but Chevy didn't always have that info as one would expect.

Rich

Rich

I have never (thank goodness) had the opportunity to trouble shoot the ajar/alarm systems, but in operations checks I have often had to fiddle (highly technical term) with the switches to make them work.

As best I recall: The rear most switch (mounted on the B pillar) operates the alarm (If so equipped) and ajar light functions.

The switch on the A pillar operates the courtesy lights.

[Richard M.]

Re: Drivers side door ajar short

Rich

I have never (thank goodness) had the opportunity to trouble shoot the ajar/alarm systems, but in operations checks I have often had to fiddle (highly technical term) with the switches to make them work.

As best I recall: The rear most switch (mounted on the B pillar) operates the alarm (If so equipped) and ajar light functions.

The switch on the A pillar operates the courtesy lights.

Terry, Ok, it looks like in 1969 the Hinge(A) Pillar switches were for the RPO UA6 alarm. Unless the AIM is wrong, I'm unsure, but it appears that way after researching further(see below info from the 1969 AIM UA6 pages, A1 to A4(below). Note Sheet A2 shows them at the firewall area, no?

So if that changed in 1972(or sooner), to be activated with the Door Ajar Warning Lamp function. I don't have the 1972 AIM so maybe Mark can post some images from it.

But, Owen sent me the hi-res image of Ernie's(Wilcox Corvette) great 1972 wiring diagram. See jpg images below the AIM images. This helps confirm Terry's knowledge and clarification of switch configuration. Thanks Terry.

Owen, thanks again for sending me the full hires image. I was able to extract, crop, and resize those 2 sections for better reading clarity.

1969 AIM
1969_AIM_UA6_A1.jpg 1969_AIM_UA6_A2.jpg 1969_AIM_UA6_A3.jpg 1969_AIM_UA6_A4.jpg


Wilcox 1972 Wiring crops.

"Rear"
Corvette1972wiring_Alarm_Rear.jpg

"Alarm" - My notes added in Red boxes
Corvette1972wiring_Alarm_CircuitWiring.jpg

Mark, so the "white" wire goes to either terminal on the door ajar switch, since it switches ground. EDIT: also to the hood pin switch. The Door Ajar lamp is activated via ground, as is the Alarm, because the lamp is alway connected to one side of the bulb filament power, with IGN on.

Rich

[Mark F.]

Re: Drivers side door ajar short

Rich, Thank you so very much. This was such a great help. I appreciate it

[Richard M.]

Re: Drivers side door ajar short

Rich, Thank you so very much. This was such a great help. I appreciate it

Your welcome...

I went in the shop a while ago and found my schematic that I made for the car alarm I designed back then as a teenager for my '69 Mustang. It's the same principle as the Corvette system, using a relay and a flasher. It saved my full box of 8-Track tapes in the back seat in Boston once. I took it into class that day at the college. I went out a while later and my horn was beeping. Driver door was unlocked and partially open.

I didn't want to drill a hole in the side of my front fender like the Corvette designers did on their rides. I mounted the Alarm key switch on the "end" of the drivers door. You had to open the door, just a little, so you could get your hand in there to reach the key to turn on or off. If the lights when on in the car that meant the door pin switches got ground and activated the latching relay, flasher, and the horns.

Later on I added a few "features" using the old-school key switch. I added a timer circuit and a delay module for the key switch. This let me have the door open, activate alarm with key, then close the door. It was about a 5 second delay circuit.

The above Corvette alarm design is quite simple and the same thing I used. With power applied to the circuit, if the hood or a door is opened, it connects ground to several points. It uses a 3 terminal horn relay. Note relay case is ground, so it has to be isolated from chassis ground(easy on a non-metal car), as case gnd gets used when it gets "latched". The relay is wired so it becomes a "Latching" relay. This means that once it's triggered, it stays "latched", maintaining the coil power to keep the 2 internal contacts closed, feeding ground to the flasher then to the horn to sound on and off. Remember one side of the horn power coil is always tied to +12V. And the flasher works in either positive or negative configuration, as the current passes through to make the flasher "flash" its load.

If you look at the Alarm Relay imagery in the Wilcox document it may be a little confusing. I'll explain with another diagram. See below.

A relay has a coil in it which when powered, it connects the internal contacts together. If one side of the coil has power at all times, i.e., when the Alarm key sends power to it from the Orange(always 12v circuit), then it has to be switched via ground. That's the principle in this design, switching ground.

Here's the re-done diagram with some notes which may help understand the principle of the Alarm "Latching Relay" circuit used back then for car alarms to beep the horns.

Corvette1972wiring_Alarm_Circuit_RelayInfo.jpg

Edit: Here's my early car alarm circuit I devised many years ago. In 1974 I sold that '69 Mustang to my girlfriend and bought a brand new '74 Gran Torino Elite, loaded. I added my DIY alarm to that one right away.
MyMustang_Torino_AlarmCircuit.jpg

One night I heard my new Torino horns beeping outside while visiting my girlfriend(the one with the Mustang). I ran out and sure enough someone used a knife to pop up the doorlock button. It had Power doorlocks, the type that was activated by pulling "up" on the doorlock button itself, or locking it by pushing it "down". The door was partially open so my alarm saved the day, I mean night.

By the way, several years later I married my girlfriend.

So I also got my Mustang back as part of the deal! Of course that wasn't why I married her....... but it was a nice perk.

Rich