Caddy STS w/ 555U and "serv. theft" light

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=23616
Printed Date: May 13, 2025 at 12:00 AM

Topic: Caddy STS w/ 555U and "serv. theft" light

Posted By: WHOP
Subject: Caddy STS w/ 555U and "serv. theft" light
Date Posted: December 30, 2003 at 11:56 AM

The dealer installed my Command Start using the 555U bypass, and although the remote starter works, but I have this damn message on my DIC (service theft...). I thought that maybe the ECM is seeing two keys once I put my key in the ignition, but that's just my guess. The delaer tried to fix the problem 5 times, and they can't figure it out, so I'll fix it if someone will help me out. Thanks guys! Does anyone have the wiring diagram for the 555U? Is there are a keysense circuit built-in?

Replies:

Posted By: sroth140
Date Posted: December 30, 2003 at 12:10 PM

what year? i went through techsoft and didnt find any install notes on it. they might have not powered up an accy wire or ign wire. or powered it up as the wrong one. i do know that some cars like a saturn sl1 (or something) needs to have an accy see (-) during remote start to prevent the check engine light, something along those lines.

Posted By: sparkie
Date Posted: December 30, 2003 at 8:41 PM

I am not familiar with the 555, but I might know what is wrong. You need to do two things. First, hook up the vehicle's key in sense wire to your remote starter's ground out when running wire. Be sure to diode isolate this line if you are using it for something else. This will trick the car into thinking it has a key in the ignition. Secondly, you must use a relay to open the pink ignition wire to the factory theft module usually located above the gas pedal. This relay should be powered by ignition and a diode isolated ground out when running line. This will prevent the car from looking for a valid transponder key in the ignition cylinder while remote started. Hope this helps.

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sparky

Posted By: WHOP
Date Posted: January 03, 2004 at 2:10 PM

Thaks for that info. Do you know what the key sense wire is? (color).