Security light stays on while driving

KINGDOMBUILDER

MEMBER
1994 CADILLAC DEVILLE
4.9L
V8
FWD
AUTOMATIC
132,000 MILES

Car starts okay and alarm system works okay but the dash security light stays on while driving. I have located the Theft deterrent and Pass-key Decoder module in trunk behind back seat and they appear okay but see that there is also a Relay Center comprised of 11 identical relays and am thinking one of these relays is bad but I do not know which one and I need a diagram of which of these relays pertains to the alarm system so I can replace it and see if that eliminates my problem. I do not know out to test relays and have no test equipment so I need to know what relay is involved with the alarm system. Or, what do you suggest may be my problem?

3 Replies

HMAC300

MECHANIC
48,601 POSTS

Try another key firstif you have one the diode may be shot on the one you use. See pic for location

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Thursday, May 15th, 2014 AT 12:47 PM

KINGDOMBUILDER

MEMBER
17 POSTS

No change with 2nd key. All the relays in the trunk are the same type relay and I would like to know if its okay to have the engine running while I pull each relay out and replace. With a new one as the diagram doesn't appear to match up exactly with the trunk relay center in my car?