Mechanics

MODELS GRAND CHEROKEE IMMOBILISER

1996 Jeep Other

Electrical problem
1996 Other Jeep Models 6 cyl Four Wheel Drive Automatic

How do I bypass the immobiliser on a 1996 Jeep Grand Cherokee. This is a RHD British market car that we imported. Made in US, though. It is made so that one needs to push the UNLOCK button on the remote every time the car is started. And now it is not working all the time. What PITA! Can I just run a wire to the starter solenoid from the key?
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Albrase
January 17, 2009.




Hello. Thanks for the donation. Much appreciated

you cannot BYPASS the immobolizer on this vehicle i'm afraid. The PCM (computer) cuts injector pulse. Not starter operation. You will need a scantool with the necassary software to diagnose the fault ! Hope this helps. Let me know

Vehicles equipped with Vehicle Theft Security System (VTSS) are protected from vehicle theft and unauthorized entry. VTSS system monitors vehicle doors, hood, liftgate and ignition. If an attempt is made to enter or operate vehicle without proper disarming of system, vehicle horn will sound, headlights, taillights and parking lights will flash, and engine will be prevented from running.
VTSS system arms when ignition is off, vehicle is exited, door is locked using power door locks and door is closed. Alternatively a remote keyless entry transmitter can be used to arm system. A security light on panel will flash for 15 seconds to indicate system is arming. At the end of 15 seconds, if no door, hood or tailgate is opened, system is armed.
If alarm is triggered, horn will sound for 3 minutes, and lights will flash for an additional 15 minutes. If horn sounds 3 times when either front door is unlocked, vehicle has been tampered with (tamper alert). If doors are locked manually or with key, system will not arm (manual override). If an unauthorized entry does occur, VTSS system signals Powertrain Control Module (PCM) to prevent vehicle from being driven. PCM reduces injector pulse width to zero, causing a start and stall condition.

***********System can be disarmed with the keyless entry transmitter, or by using key to enter vehicle. In both instances, if alarm was activated, vehicle alarm will be terminated. If battery is disconnected and reconnected, alarm will be activated and it will be necessary to disarm system as indicated.****************

ANTI-THEFT SYSTEM TEST 1A - IDENTIFYING ANTI-THEFT SYSTEM PROBLEMS
NOTE: Perform SYMPTOM ID TEST 1A before proceeding. For connector terminal ID, see CONNECTOR IDENTIFICATION and WIRING DIAGRAM. See ANTI-THEFT SYSTEM article. Perform TEST VER-2A after each repair.

CAUTION: Always turn ignition switch to OFF position prior to disconnecting any module connector. Ensure all connectors are clean and tight.

NOTE: Anti-theft system may also be referred to as VTSS (Vehicle Theft Security System).

Using scan tool, select BODY SYSTEM, then BODY COMPUTER. If scan tool displays BUS OPERATIONAL, go to next step. If scan tool displays NO RESPONSE, go to TEST 3A under VEHICLE COMMUNICATIONS. If scan tool displays any other message, go to TEST 1A under VEHICLE COMMUNICATIONS.
If anti-theft indicator light comes on while driving, go to ANTI-THEFT SYSTEM TEST 2A. If anti-theft indicator light stays on during arming process, go to ANTI-THEFT SYSTEM TEST 8A. If okay, go to next step.
Using scan tool, select MODULE DISPLAY. If module ID is not ZJ BODY BCM W/VTSS, go to ANTI-THEFT SYSTEM TEST 3A. If okay, go to next step.
Using scan tool, select THEFT ALARM. Turn ignition on. With scan tool in THEFT ALARM, select MONITOR DISPLAY. Read VTSS status. If VTSS mode is not disarmed, go to ANTI-THEFT SYSTEM TEST 1B. If scan tool displays powertrain control module 1 - NO RESPONSE/2 -NO RESPONSE, go to TEST 9A under VEHICLE COMMUNICATIONS. If okay, go to next step.
Ensure all doors are closed and properly aligned. Turn ignition off. DO NOT remove key from ignition switch. With scan tool still under THEFT ALARM, select MISCELLANEOUS, CHANGE MODE, then DIAGNOSTICS. After entering DIAGNOSTICS mode, horn should sound twice, park lights and headlights should flash, and anti-theft indicator light should flash. If the horn fails to sound, go to ANTI-THEFT SYSTEM TEST 4A. If anti-theft indicator light fails to flash, go to ANTI-THEFT SYSTEM TEST 5A. If headlights or park lights fail to flash, go to ANTI-THEFT SYSTEM TEST 6A. If okay, go to next step.
Remove key from ignition switch. Park and headlights should stop flashing. Open and close each door, liftgate and hood. Rotate key in front doors and liftgate to unlock position. Horn should sound. If horn does not sound after each action, perform indicated tests specified in ANTI-THEFT SYSTEM DIAGNOSTIC TEST DIRECTORY.
TEST VER-2A - VERIFICATION PROCEDURE
Ensure all doors and liftgate are closed. Open driver's door. Remove ignition key. Lock doors with remote keyless entry transmitter. Close driver's door. If anti-theft indicator light flashes, system is operational. If anti-theft indicator light does not flash, perform ANTI-THEFT SYSTEM TEST 1A.

Dave H
Jan 18, 2009.
Thanks, That gives me some place to start. Come to think of it, I just ASSUMED it was the immobiliser. It just won't operate the starter. It could actually be most any other part in that line, I guess. The scan tool might point me in the right direction.
We have had incredibly cold temps, here, down to -34F on Friday. But this starter thing has come up often for the last 6 months.
Al

Tiny
Albrase
Jan 18, 2009.
I would be checking. Starter motor wiring connections. Ignition switch for faults/sticking. You could also check neutral safety switch connections? Let me know if you need any diagrams listed? .

ON-VEHICLE TESTING
CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

CRANKING TEST
NOTE: Ensure engine is at normal operating temperature. High viscosity oil, extreme cold temperatures, or tight engine will increase amperage draw.

Using a battery load tester, connect positive and negative leads to battery. Connect inductive ammeter pick-up to positive battery cable. Ensure all lights and accessories are off. Place A/T in Park or M/T in Neutral. Apply parking brake.
Crank engine and observe voltmeter reading. If voltage drops below 9.6 volts, recharge and test battery. If voltage remains above 9.6 volts, observe amperage reading. Replace starter if amperage draw is more than specified. See STARTER SPECIFICATIONS.
CAUTION: During cranking, DO NOT draw battery voltage down to less than 9.6 volts. Use care not to overheat starter.

If starter cranks engine freely, but problem with starter is still suspected, engage starter several times while observing volt/ammeter readings. A starter that has a problem should fail when performing this procedure.
CIRCUIT RESISTANCE TESTS
NOTE: If excessive resistance is not found in circuits being tested, remove starter and proceed to BENCH TESTING.

NOTE: A voltmeter accurate to one tenth of a volt will be needed for the following tests.

Battery Connection Resistance Tes
Connect voltmeter positive lead to negative battery cable clamp. Connect voltmeter negative lead to negative battery post. Crank engine and observe voltmeter reading. If voltage is greater than 0.2 volt, repair poor contact between cable clamp and post. Perform same procedure to positive battery post and cable clamp.
Ground Connection Resistance Test
Connect voltmeter negative lead to negative battery post. Connect voltmeter positive lead to engine block, near negative battery cable grounding point. Crank engine and observe voltmeter reading. If voltage is greater than 0.2 volt, repair poor ground connection or replace ground cable.
Starter Ground Connection Resistance Test
Connect voltmeter negative lead to negative battery post. Connect voltmeter positive lead to starter housing. Crank engine and observe voltmeter reading. If voltmeter reading indicates more than 0.2 volt, repair poor starter-to-ground connection.
Positive Battery Cable Resistance Test
Remove starter heat shield (if equipped) to gain access to starter solenoid connections. Connect voltmeter negative lead to starter solenoid battery terminal and voltmeter positive lead to positive battery post.
Crank engine and observe voltmeter reading. If voltage reads more than 0.2 volt, correct poor connection between battery cable and starter solenoid or replace positive battery cable.
SOLENOID CIRCUIT TEST
NOTE: Perform SOLENOID CIRCUIT TEST under ON-VEHICLE TESTING before testing starter relay circuit and starter relay. Ensure A/T is in Park or M/T is in Neutral and parking brake is applied.

Ensure battery is fully charged. Ensure solenoid connections are not loose or corroded. Remove starter relay from Power Distribution Center (PDC). Refer to PDC cover for proper relay location. PDC is located in engine compartment.
Connect a remote starter switch or jumper wire between starter relay connector terminal No. 87 and positive battery post. See Fig. 1. If engine cranks, solenoid and starter are good. Go to STARTER RELAY CIRCUIT TEST.
If engine fails to crank, or if solenoid chatters, check wiring and connectors from starter relay connector to starter solenoid terminal for loose or corroded connections. Clean and retest. If engine still fails to crank, remove starter and proceed to SOLENOID TEST under BENCH TESTING.
Fig. 1: Identifying Starter Relay Terminals
Courtesy of CHRYSLER CORP.
STARTER RELAY TEST
NOTE: Perform SOLENOID CIRCUIT TEST under ON-VEHICLE TESTING before testing starter relay.

Remove starter relay from Power Distribution Center (PDC). PDC is located in engine compartment. Refer to PDC label for starter relay identification.
Using an ohmmeter, check for continuity between starter relay terminals No. 30 and 87A. See Fig. 1. If no continuity exists, replace starter relay. Check for continuity between starter relay terminals No. 30 and 87. If continuity exists, replace starter relay. If relay tests as specified, go to next step.
Check resistance between starter relay terminals No. 85 and 86. If resistance is not 70-80 ohms, replace starter relay. If resistance is okay, go to next step.
Connect a 12-volt power source to starter relay terminals No. 85 and 86. Continuity should exist between starter relay terminals No. 30 and 87. No continuity should exist between starter relay terminals No. 30 and 87A. Replace starter relay if it does not test as specified. If starter relay tests as specified, go to STARTER RELAY CIRCUIT TEST.
STARTER RELAY CIRCUIT TEST
NOTE: Perform SOLENOID CIRCUIT TEST under ON-VEHICLE TESTING before testing starter relay circuit.

Ensure battery is fully charged. Remove starter relay from Power Distribution Center (PDC). Refer to PDC cover for proper relay location. PDC is located in engine compartment.
Connect a jumper wire between starter relay connector terminals No. 30 and 87. See Fig. 1. If engine does not crank, go to SOLENOID TEST. If engine cranks, go to next step.
Turn ignition on. Check for battery voltage at starter relay connector terminal No. 30. If voltage is not present, repair open in wiring from starter relay connector to battery.
If voltage is present at starter relay connector terminal No. 30, ensure battery voltage is also present at starter relay connector terminal No. 86. Check for voltage with ignition switch in START position. If voltage is not present, go to next step. If voltage is present, circuit is okay. Go to step 6).
If voltage is not present at starter relay connector terminal No. 86, repair open or short in wiring from ignition switch to starter relay connector. If circuit to ignition switch is okay, check ignition switch. See IGNITION SWITCH TEST under ON-VEHICLE TESTING.
Check for continuity to ground at starter relay connector terminal No. 85. If continuity exists, circuit is okay. If continuity does not exist, go to next step.
If vehicle is equipped with an A/T, check for an open or short to neutral safety switch. See NEUTRAL SAFETY SWITCH under ON-VEHICLE TESTING. If vehicle is equipped with a M/T, repair circuit to ground as required.
IGNITION SWITCH TEST
WARNING: Deactivate air bag system before performing any service operation involving steering column components. See appropriate AIR BAG RESTRAINT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section.

NOTE: For additional information, refer to TEST NS-1A in appropriate TESTS W/CODES article in ENGINE PERFORMANCE section.

Disconnect negative battery cable. Remove ignition switch. See STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. With ignition switch in ON position, check for continuity between ignition switch terminals No. 1 and 7. See WIRING DIAGRAMS. If continuity exists, replace ignition switch. If continuity does not exist, go to next step.
With ignition switch in START position, check for continuity between ignition switch terminals No. 1 and 7. See WIRING DIAGRAMS. If continuity exists, ignition switch is okay. If continuity does not exist, replace ignition switch.

Dave H
Jan 18, 2009.
I got it to start! I left the battery disconnected overnite. When I hooked it up, it started (after pressing the " unlock" button on the fob.)
I'd unhooked the battery before, but apparently it must have rebooted this time?
A mystery to me. Thanks. I've printed out your replies and no doubt will need them soon.
Al

Tiny
Albrase
Jan 18, 2009.
SNAP. I have exactly the same problem: Jeep wont start, then disconnect the battery for certain period of time, then it starts. Then the periods for disconnect were longer and not always worked.

Now it wont start at all. The only way to start the engine is to tow the jeep, then it starts and I can drive it. Until I tirn the key off. Then wont start again

Please help!
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Tiny
Pimmy
Nov 30, 2011.
You need to start a new question of your own please.

Wrenchtech
Nov 30, 2011.
Hi, for both of you who are experiencing this problem this post might very well help.
I have a Jeep Grand Cherokee 1996, 5.2l engine. I have found that the VTSS in that vehicle is disabled every time you either use the keyfob (unlock button) or the key to unlock either front door. Well in my car it happened that neither way worked. It turned out to be that the keylock in the drivers' side had its inner contacts worn out. It is designed so that when unloking the door its two contacts make a temporary contact (a fraction of a second). During such contact, the signal coming from the module is sent to ground, dissabling all VTSS so that you can enter and operate the engine. Since I had no money to go to the dealer this is how I fixed it: I put a lever switch inside the door panel located in such a way that it would close each time the door is locked and unlocked. Such switch remains clamped if the door remains locked and remains open if the door remains open. Next, with the switch working that way, I need to create a temporary connectiont o ground for the purple line the keylock has. To do that I triggered open a transistor through a little capacitor each time the new switch toggled. It worked just fine since then. I've had had no problems anymore with the VTSS. If anyone wants to see more details of how I connected the new lever switch and transistor and capacitor, just let me know o do that in this post and I will be really happy to scan my handwritten notes of this repair for you. These three components were installed without uninstalling the old, worn out key lock on the drivers door.

Tiny
Ernesto123
Jun 19, 2012.
This is a 2 year old thread. I doubt his car is still stuck.

Wrenchtech
Jun 19, 2012.

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