1995 Chevrolet Corvette Service & Repair Manual

ANTI-THEFT SYSTEM 1995 ACCESSORIES & SAFETY EQUIPMENT General Motors Corp. Anti-Theft System DESCRIPTION & OPERATION ANTI-THEFT SYSTEM Vehicle is equipped with Universal Theft Deterrent (UTD) and Personalized Automotive Security System (PASS-Key(R)) anti-theft systems. With UTD system, SECURITY light will flash as door is opened (if ignition is off). This light reminds driver to arm theft deterrent system. If a door or hatch is opened, alarm will sound and vehicle will not start. If SECURITY light does not flash on, then off, system is not armed. PASS-Key(R) is a passive theft-deterrent system which works with a resistor pellet in ignition key which matches an in-vehicle decoder. If PASS-Key(R) system senses wrong key is being used it shuts down vehicle's starter and fuel system for 3 minutes. If someone tries to start vehicle again or uses another key during this time, shutdown period will start over again. COMPONENT LOCATION UTD COMPONENT LOCATION UTD COMPONENT LOCATION TESTING SYSTEM TEST WARNING: Vehicle is equipped with driver and passenger air bags. Before attempting ANY repairs involving steering column or related components, see SERVICE PRECAUTIONS and DISABLING & ACTIVATING AIR BAG SYSTEM in the AIR BAG RESTRAINT SYSTEM article. Component Location Central Control Module (CCM) Behind Middle Of Instrument Panel Clutch Start Switch Mounted On Each Side Of Clutch Pedal Assembly Door Key Switches In Each Door, At Key Lock Cylinder Engine Control Module (ECM) Left Rear Of Engine Compartment Hatch Ajar Switch Rear Of Cargo Compartment, On End Panel Horn Relay Below Right Side Of Instrument Panel Key-In-Ignition Switch Top Of Steering Column, Below Turn/Hazard Switch Assembly Passive Keyless Entry (PKE) Module Under Top Left Side Of Instrument Panel Starter Enable Relay Below Left Side Of Instrument Panel, Left Of Steering Column

UTD Will Not Arm 1. If power door locks do not operate, see DOOR LOCKS - POWER article. If power door locks do operate, use Tech 1 scan tester to monitor power door unlock and lock inputs. 2. Using right and left door lock switches, lock/unlock doors. If scan tester does not indicate unlock and lock inputs as doors are being unlocked and locked, check for poor connection at CCM connector C1, terminals "B" (Tan wire) and "D" (Gray wire). If connection is okay, check Tan and Gray wires for open circuit. If wiring is okay, replace CCM. 3. If scan tester does indicate lock/unlock inputs, monitor door ajar and hatch ajar inputs. If scan tester does not show transition of door ajar and hatch ajar inputs as doors and hatch are opened and closed, go to DOOR AJAR & HATCH AJAR SWITCH TEST. 4. If scan tester does show transition of door ajar and hatch ajar inputs, use Tech 1 to monitor door key inputs. If Tech 1 scan tester does not correctly show transition of right and left door key switches as key is turned, go to UTD SYSTEM WILL NOT DISARM WITH DOOR KEY test. 5. If Tech 1 scan tester does correctly show transition of right and left door key switches, discontinue diagnostics. Turn ignition switch to RUN position. If PASSIVE KEYLESS ENTRY telltale does not illuminate on Driver Information Center (DIC) during bulb check, diagnose keyless entry system. See KEYLESS ENTRY SYSTEM article. 6. If PASSIVE KEYLESS ENTRY telltale does illuminate on Driver Information Center (DIC) during bulb check, check if power door locks unlock and lock when passive keyless entry transmitter is brought into range and out of range. If doors do not lock and unlock, see the KEYLESS ENTRY SYSTEM article. 7. If doors do lock and unlock, leave connector connected and measure voltage between Passive Keyless Entry (PKE) module Gray connector C2, terminal B1 (Yellow wire) and ground. If voltage is approximately 12 volts, go to step 9). 8. If voltage is not approximately 12 volts, disconnect PKE module Gray connector C2. Measure voltage between terminal B1 (Yellow wire) and ground. If approximately 12 volts are present, replace PKE module. If approximately 12 volts are not present, check for short to ground in Yellow wire to CCM. If wire is okay, replace CCM. 9. If voltage is approximately 12 volts in step 7), continue to probe terminal B1 to ground. Set voltmeter to detect minimum voltage on millisecond range. Close doors and hatch. Move PKE transmitter out of range. 10. If voltage changes from approximately 12 volts to approximately .5-1.0 volts when doors lock, replace CCM. If voltage does not change as indicated, check for poor connection at PKE module connector. If connection is okay, replace PKE module. Door Ajar & Hatch Ajar Switch Test 1. Use Tech 1 scan tester to monitor power door unlock and lock inputs. Open and close both doors and hatch. If Tech 1 inputs correctly change status as doors and hatch are opened and closed, no problem is found. NOTE: Before performing any testing, ensure appropriate fuse(s) and instrument panel bulb for SECURITY indicator light are good. For location of UTD components, see UTD COMPONENT LOCATION table.

2. If Tech 1 inputs do not correctly change status as doors and hatch are opened and closed, check if one or more Tech 1 input always indicates door is closed or open. If input indicates door is open, go to step 5). In input indicates door is closed, go to next step. 3. Disconnect switch where problem is occurring. Connect a fused jumper wire between door ajar switch terminal "A" (Black/Yellow or Black/White wire) and ground, or between hatch ajar switch terminal "B" (Black/White wire) and ground. If Tech 1 input does not change from closed to open, check for an open circuit between switch connector and CCM. If an open circuit is not present, replace CCM. 4. If Tech 1 input does change from closed to open, connect a fused jumper wire between suspect switch terminals. If input changes from closed to open, replace suspect switch. If input does not change from closed to open, repair open circuit in Black/White wire. 5. If one or more input always indicates door is open in step 2), disconnect suspect switch connector. If input now indicates open, replace suspect switch. 6. If CCM diagnostic input does not indicate open, check for continuity between terminal "A" (Black/Yellow or Black/White wire) of suspect door ajar switch connector or terminal "B" (Black/White wire) of hatch ajar switch connector and ground. If continuity is present, repair short circuit to ground. If continuity is not present, replace CCM. UTD System Will Not Disarm With Door Key (Left, Right Or Both) 1. Use Tech 1 scan tester to monitor door key input. Cycle door key switches. If Tech 1 input correctly changes status when door key switch is cycled, no problem is found. 2. If input does not correctly change status when door key switch is cycled, check if switch input always indicates on or off. If input is always on, go to step 6). If input is always off, go to next step. 3. Disconnect left door key switch. Use a test light and probe left door key switch connector terminal "B" (Black/White wire) to battery voltage. If test light does not light, repair open circuit in Black/White wire. 4. If test light does light, connect a fused jumper wire between left door key switch connector terminals "A" (Light Green wire) and "B" (Black/White wire). If door key switch input does not indicate on, check for an open circuit in Light Green wire to CCM. If wire is okay, replace CCM. 5. If door key switch input indicates on, replace left door key switch. Repeat test and diagnose right door key switch only. 6. If input is always on in step 2), disconnect left door key switch. If door key switch input indicates off, replace left door key switch. 7. If door key switch input does not indicate off, disconnect right door key switch. If door key switch input indicates off, replace right door key switch. If door key switch input does not indicate off, disconnect Passive Keyless Entry (PKE) module connector C2 (Gray connector). 8. If door key switch input indicates off, replace PKE module. If door key switch input does not indicate off, check for short to ground in Light Green wire to CCM. If wire is okay, replace CCM. UTD System Arms But Does Not Sound Alarm During Illegal Entry 1. Leave driver's window open. Ensure ignition is off. Arm theft system by opening door, locking it, then

closing door. Connect a test light between horn relay connector terminal No. 85 (Black wire) and battery voltage. 2. Reach in through open window. Unlock and open driver's door. If test light flashes on and off about once a second, diagnose and repair horn. If test light does not flash, check for an open circuit in Black wire between horn relay connector and CCM. If wire is okay, replace CCM. SECURITY Indicator Does Not Illuminate (Theft System Appears To Operate Okay) 1. Remove instrument cluster. See procedures in the INSTRUMENT PANEL - ELECTRONIC article. Connect a test light between instrument cluster connector terminal B12 (Brown/White wire) and voltage. Ensure key is removed from ignition switch. 2. If test light does not flash on and off when left or right door is opened, check for an open circuit in Brown/White wire between instrument cluster connector terminal B12 and CCM. If wire is okay, replace CCM. 3. If test light does flash on and off when left or right door is opened, connect a test light between instrument cluster connector terminal B13 (Orange wire) and ground. 4. If test light lights, check SECURITY indicator bulb. If bulb is okay, repair/replace instrument cluster as necessary. If test light does not light, check for an open or short circuit to ground in Orange wire. If wire is okay, check for an open fuse. PASS-Key(R) Lock Cylinder & Harness Test 1. Remove hush panel under steering column. Disconnect PASS-Key(R) 2-pin connector in wire leading to steering column. 2. Connect male and female parts to mating connectors on pigtails from Interrogator (J 35628). Insert ignition key into ignition switch. Press ON-OFF switch on interrogator to ON position. Window above key code reader should indicate electrical code for key (1 through 15) or "E" for error. 3. Rotate ignition key to ensure correct code is read in all positions. If code is correct in all positions, set interrogator key code selector to same electrical code displayed in step 2). Turn ignition switch to START position. 4. If code is correct only in some positions, obtain a spare key or make a replacement. Read code again. If code is correct, original key was defective. An incorrect code indicates a defective lock cylinder. 5. If display window shows "E", check ignition key by inserting it in interrogator key code reader. If interrogator indicates "E", replace key. If interrogator indicates electrical Codes 1 through 15, replace lock cylinder. Pass Key Resistance Values CAUTION: Ensure correct PASS-Key(R) 2-pin connector is disconnected and not Yellow 2-pin Supplemental Inflatable Restraint (SIR) connector. PASS-Key(R) 2-pin connector has Purple/White and White/Black wires.

REMOVAL & INSTALLATION CENTRAL CONTROL MODULE (CCM) Removal & Installation 1. Disconnect negative battery cable. Remove driver side knee bolster and inner bracket. Unclip fuel pump relay No. 2 from relay bracket and place out of the way. 2. Slide CCM to left and tilt up to access harness connectors. Disconnect harness connectors from CCM. Continue to slide CCM to left, tilt downward 45 degrees, and remove. To install, reverse removal procedure. TROUBLE SHOOTING 1. Ensure all ground connections are clean and tight. If theft deterrent system operates normally using power door lock switches but not with keyless entry transmitter, see the KEYLESS ENTRY SYSTEM article. 2. Ensure key-in-ignition warning chime operates properly. Check for Central Control Module (CCM) diagnostic trouble Codes 51, 52, 53, 54, 61 or 63. If codes are present, see the INSTRUMENT PANEL - ELECTRONIC article. 3. Ensure horns operate correctly. Check for broken or partially broken wires. Ensure doors and rear hatch are fully closed. Check for incorrect installation of aftermarket electronic equipment. 4. Ensure power door lock system operates normally using power door lock switches. See the DOOR LOCKS - POWER article. If alarm sounds when keyless entry transmitter is brought into range, check for short to ground in Dark Green wire at CCM terminal F6. WIRING DIAGRAMS Key Resistance Number Ohms Value 1 402 2 523 3 681 4 887 5 1130 6 1407 7 1870 8 2370 9 3010 10 3740 11 4750 12 6040 13 7500 14 9530 15 11800

Fig. 1: Anti - Theft System Wiring Diagram

1995 Chevrolet Corvette Service & Repair Manual

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