R CRYSIS

Hi I have a C5 Vette and I have learned about most of there glitches but I was wondering if I could get some help from the C4 guys with my friends 92 convertible. When he unlocks the door with the key on the drivers side it sets off the alarm. If he unlocks the passenger side it does not. He called me and asked if I could install a new drivers side door lock for him that he has already purchased witch I told him I would but I want to make sure that is the problem before I take the car apart. My question is are there certain connections or fuses I should check first is this a common problem with the C4 and also I was wondering if the new lock has to be coded to the chip in the key so the alarm won't go off. I have not seen the part yet so I am not sure exactly what he got. I would appreciate any help or advice you could give me so I'm not going into this thing blind....Thanks

markKlein

The door key is a separate key, no chip on that one. Does the drivers lock work electrically, or just manually? Have you checked all of the fuses? It isn't that big a deal to pull the door panel, so if he has a new lock already, I'd start there. Of course, an FSM would be a big help.

R CRYSIS

Thanks for the info any help is appreciated as far as I know the electronic door locks work fine. The only problem it the alarm on the drivers door. Your right I have had the door panels off of a C4 in the past to replace a power window motor and it wasn't that bad. He is bringing the car over this weekend so I will check all of the connections and fuses also before I go to far. I wasn't sure if this could be a B.C.M problem or not. The C5 Vettes are known for having some issues with them. I am hoping it's just a bad switch.

Hooked on Vettes

You might want to verify he got the correct part. The switch is
door specific (left or right door switch).

The switch is held on to the back of the key cylinder by a e clip.
When the door key is turned to the unlock position, the theft switch closes.

The switch has two wires. Black wire goes to ground.
Light Green wire goes to the CCM to disarm the alarm.

If you open the drivers door, the Security light on the dash cluster
blinks. If you lock the doors using the power door locks the Security
light will go solid. That indicates when the door is closed the alarm
will be set.

With the door still open if you turn the door key to unlock the
Security light will start blinking again indicating the alarm has
been reset and will not set when the door is closed.

If the security light remains solid the theft switch is not working.
You could try turning the key back and forth a dozen times and
see if that cleans off the contact surface of the switch.

Here's a picture of the switch and the parts identification.
Also there is a picture of the replacement switch which comes with the
harness.

To gain access to remove the switch requires removing that tin sheet
metal plate off of the door.

R CRYSIS

Wow! Thanks for all of the information it was very helpful. I will check the part against the picture you posted when he brings the car over this weekend. I have a good idea of what I am looking at now it will make it much easier

R CRYSIS

Got the car fixed wanted to say thanks again for the help the information came in handy. I was able to replace the alarm switch on the end of the lock without taking off the metal plate in the door. I took the two small screws off of the weather strip on the edge of the door and peeled it away and I was able to get the snap ring off and get the switch out that way. When I was done I just re glued it and put the screws back in...seems to work fine now

myrononthego

Hello everyone, A friend of mine bought a 87 C4 and the issues with it as well. His alarm will not turn off with the door key on the driver’s side. So to diagnose the problem we took the door apart and took the alarm switch off. Since the passenger side works we took it off as well and tried it on the driver’s side and it worked… well sort of since it is a LH or RH lock it would disarm when locking the door but at least we knew it was the switch that was not working on the driver’s side. So he cleaned the working switch with a wire brush and surprise the passenger one now doesn’t work as well. So we are ordering both sides and will install them when they come. I decided to take apart the one that I knew didn’t work and cleaned it all up and thought let’s see is it works and to my surprise it did but when I tried to install the C Clip I for the life of me couldn’t get it back on. I even took of the inner panel but still did not have the space to get it in correctly. The car ended up eating about 6 clips now and half of my hand. Is there and tool for c clips not snap rings? And is there a special way the switch should line up correctly? Should the key be in a special position as and before installing the new switch? If anyone has any pictures or videos of How To would be very very helpful. I’m a bit disappointed with myself because we worked on this the whole weekend and now he has 2 doors that don’t work and I want to make sure we do it correctly when he gets the new switches. Thanks in advance for your help
Myron

R CRYSIS

When we did my friends car(A 92) a few weeks ago I had the same problem trying to get the clip back on. I have kinda big hands and I made hamburger out of them trying to get my had in to get the clip on. I finally took the two screws out of the rubber weather striping on the edge of the door and peeled it away to get better access through the hole underneath and I was able to get the clip on first shot. also make sure that the switch is all of the way on the cylinder and the two little white clips on the sides have snapped in that way you make sure that the grove for the ring id fully exposed. I also used a magnetic screwdriver to hold the clip I was able to put it part way in the grove and snap it in with another screwdriver from the top through the access I had made by removing the weather strip from the corner of the door. When we were done I just glued it back on and replaced the two screws. Hope this helps....

myrononthego

I will try that as-well and thank you for that information, Anyone know if the key should be in a particular position when installing the new switch?