Angel1000, I'm afraid I can't help you much the the details on an '84, but if I might make a general suggestion; many of the questions you are asking are answered in the owners manual. If your car didn't come with one you should be able to find one pretty cheaply on eBay or some other site. Aside from possibly helping you understand how the alarm system (the alarm and anti theft systems are separate systems, at least on the later model C4s) is supposed to work you might also find out interesting facts about parking brakes, arm rest storage, hatch buttons and other unique features.

 

From the 84 FSM, hope this helps..

 

I was looking through some C4 wiring diagrams I have and found this. I showed it to a friend who is an electrical engineer and told him the problem you are having. He said that since the horn always has power to it and should only blow when you press the horn button to create a ground yours is grounding some where else. Since the theft deterrent system is powered through the door locks to the door lock relay assembly and the horn could get grounded through that assembly it is very likely your problem.
Its something else to look at and I hope it helps.
Pa

 

The SECURITY light will flash if the door is open and the TDS is NOT armed.
The SECURITY light will stay on steady if the door is open and the TDS IS armed.
The SECURITY light will go out if the door is closed or the ignition is turned on. It appears that this is not happening in your case. The switch that tells the TDS that the door is closed is located on the hinge pillar.

I don't think the TDS is affected by disconnecting the battery. Usually you disconnect the battery to reset something controlled by a microprocessor. That would be the ECM, dash and radio. I never took a TDS apart so I don't know what's inside. My car has VATS, which I DID take apart...

 

3 short beeps is NOT stock. You have an aftermarket alarm on your car.

It's TDS with a "D" in the middle for Theft Deterrent System...

 

The SECURITY light should go out as soon as you close the door.

For reference, the TDS module is located behind the "bread loaf" on the passenger side of the dash:



The relay in the metal clips in this pic is the horn relay:

 

Yes, those beeps were the radio. Silly me!
Thanks for the referral thread. Helpful.


Did you see my latest post? Any comments? Want to by a LEMON? CHEAP!!!

 

Thanks so much! And thanks to your EE friend!
Great diagram for me to have in my file, as it relates.
I see clearly now how the TDS gets its signal to arm (From Horn supply circuit through the door lock relay assembly, in route to the door lock motor). Since the door lock/unlock (via the electric door lock switches) functions normally, the circuit is complete. The TDS gets the signal that the electric door lock/unlock button was used, but this information is only used to arm the system. Once in active alarm mode (My situation, horn relay energized and starter disconnect relay active), the door key switch signal is the only unarm devise/signal needed to turn alarm status off, right?


Questions:
1) Perhaps your EE friend can help with this one?
Horn relay operation: I assume a horn relay (Normally Open SPST) is used whether or not one has a security system? The horn (+) is constant to one side of the relay switch and one side of the relay control coil. The negative (-) controls it's status. a) Momentary Negative (-) contact from the steering wheel horn button activates the coil and closes the (+) connection through the relay switch to the actual horn. Making the horn sound.
b) Constant Negative (-) signal from the TDS (In alarm mode) to the horn relay coil holds the relay switch closed to allow constant (+) connection through the relay to the actual horn. Horn sounds. I understand there is some "time out" function here. In alarm mode the horn will time out, to save battery, but the starter interrupt relay will remain active until door key switch is used to turn alarm mode off.
I have now unplugged the TDS module (found behind the passenger crash pad).
I have also disconnected the starter interrupt relay (found behind the CID information center) and jumped out the start wires (Purple) of the starter interrupt relay connector.
I have unplugged the horn relay. (It was very hot and draining my battery over night). I also reconnected the wiring at the horn. (Someone had previously disconnected them)


TDS disabled, The car now starts and runs, however, when I reinstall the horn relay the horn sounds immediately and will not stop. In other words, I am unable to make the horn button on the steering wheel work on it's own.
Do you, or anyone, have a schematic of this horn circuit, with TDS installed. Something must still be providing a ground to the horn coil?? It is not coming from the steering wheel switch (I disconnected that).


After running the engine, it started overheating. Another issue... Argh!!!
The previous owner (Hereafter referred to as "JERKO.") must have had a failure of the electric engine cooling fan. I see he ran a very thin wire from the fan (+) to the alternator 'field' wire in effort to keep fan on. This wire burned to a crisp! Jerko never mentioned this to me, this... field alteration! Guess he just forgot, like he forgot to mention the security system problem???? Hummm, what else did Jerko forget to tell me???
Anyway, the neg (-) is good. The other fairly heavy gauge (Black) wire (+) has no power to it.
a) Does the fan run constant or switch on and off as needed?
b) Where does it get power? Power wire (black) seems to run inside a fairly fat harness from fan area over the drivers side wheel well and through the firewall into the driver under dash area???
c) Seems there should be more circuit breakers/fuses for this car than the few located by passenger side dashboard fuse box. Perhaps there is an inline fuse for this fan circuit SOMEWHERE??


As always, thank you guys so much for ALL your help here! Couldn't solve these problems without it!


Have a GREAT JULY 4TH WEEKEND!!
Angel
PS: I will take a break from this project until Monday.

 

Sounds like you're the new owner of a Bubba Mobile.

I was under the impression the factory alarm would pulse the horns.
If the horns are on constant something is grounding the control side of the relay coil negative side.



Schematic of the Cooling fan.




Diagram showing location of coolant fan switch.
The fan can be turned on by the switch on the back of the AC compressor when the AC high pressure exceeds a certain PSI or by the temperature fan switch screwed into the head.

 

Right to the point!! I love it!
I will certainly be able to solve these problems, given these diagrams.
Thank you so much and Happy 4th!
Angel
PS: Can't wait to see that Jerko, Bubba, again!! LOL

 

The fan is controlled by a coolant temperature switch in the passenger side head, located between spark plugs #6 and #8.

There are several fusible links (30 amps) for various things. I'm not sure where the junction block for those links is located on an '84. It might be on the firewall somewhere. There should be a fairly heavy red wire from the positive battery terminal to the junction block.

 

That's interesting. I didn't know you could do that. I thought it would arm no matter how you locked the door.

I did test it and it does function the way you describe.

 

From HOV'S drawing in post #30, the switch is located in the passenger side block left of the dipstick on the 84..

 

Youre right on the 84 its on the passenger side.

 

Hi, sorry I didn't get back to you sooner, I just got the notification that you posted. I see you have made some progress and found and bypassed the starter relay. Have you found the security module yet? I seems you are looking in the right place. If you need to know what it looks like, I can take a picture of mine. I saved it after I took it out.

No, I don't think there is a high theft rate on these cars, but it would be nice if the security system worked. I suppose the module could be replaced, but I don't know where to get one.

Once set, the system is activated by opening either door. Not sure about the hatch. My system armed itself without me setting it, then activated itself with the doors closed! I just decided to delete it and not worry about it.

 

Also, the security system would not blow the horn all the time. I had the constant horn blowing problem as a separate issue, and it was in the steering column. There is a plastic insulator in there that falls apart, causing the horn to blow. This may be your problem.

 

Hope you ALL enjoyed your July 4th holiday!
Tomorrow I'm back to work on my "pesky" vet...
Yes, there is a heavy red wire (Maybe 8awg or so) connected to the (+) battery, in addition to the very heavy cable (Maybe 4 or 2 awg).
I assumed had assumed the smaller red ultimately fed the fuse block, passenger door dash area.


Great, I now know where to look for the temperature switch (Near dipstick). I the event it is functioning, next I would be looking at the fan relay. Any idea where the fan relay will be found, short of tracing the switch wires and/or the fan wiring through the harnesses?


So, I also just read (in the next thread post) that I will have difficulty replacing the TDS control module, should I find it damaged and wish to restore the security system to it's original condition. If this is so, then I might as well just stop my investigation as to what exactly failed here and do what I must to make the horn work.


A summary of my questions for this day...
1) Will I be able to replace the TDS module?
2) Where will I find the fan relay? And please, don't tell me..."The last place you look!" Ha Ha
3) Location of any additional fuse blocks? IE: Fuses not contained in the normal fuse block by the passenger door dash? (It was mentioned there "may" be one on the firewall. I don't recall seeing one on the engine side of the firewall...
Or, is there simply a bunch of randomly located in-line fusible links throughout?


Thanks again to ALL,
Angel

 

I will certainly check this insulator out. I assumed it was a TDS issue because the starter interrupt relay was also held in the energized mode??
Thanks,
Angel

 

Welcome back!
As noted (above), if I cannot replace the TDS module (If determined to be broken) then there is no point in continuing this investigation, I will simply leave it disabled and move toward fixing the horn issue.
Thanks,
Angel


PS: In effort to eventually pass an inspection... I will next be trying to figure out why one headlight assemble (Driver side) flips perfectly and reliably, while the other (passenger side) flips only now and again, sometimes only half way and most times not at all?? The headlamps both light every time...

 

I see the security system module on ebay for $30-$50 if you really want to have it.

Wonder if anyone has the circuit diagram here?