1996 Cadillac DeVille - Answered Questions & Fixed issues

Question edited for clarity. Question moved to model category. It is in the engine compartment Fuse and Relay Center. However, it may not be that but good place to start. https://www.google.com/search?q=1996+cadillac+deville+starter+relay+location Test, don't just blindly replace components. https://www.google.com/search?q=1996+Cadillac+Deville+no+crank+no+start Best idea by far. A pro grade scan tool computer can diagnose in 20 minutes https://www.google.com/search?q=mobile+auto+electrician+near+me ..

Have the transmiision serviced with new fluid and a filter. Also do a OBD2 ele ctronic system control fault code test with a scanner or code reader.

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It takes special equipment and a GM service subscription to program the replacement PCM.

You will have to replace the ign. lock cylinder

Could it be as simple as spark plugs and wires need updated/cleaned?

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It means you should try replacing the engine coolant temperature sensor as it has probably failed (it's located on the driver's end of the engine at the middle about half way down).

Check and/or change plugs and wires...or relocate starter relay to inside engine bay...cheers.

run the fault codes to see what has failed saves time and money

Unfortunately, it sounds like your HVAC control module is failing. You can try a reset by removing the negative battery lead (under the rear seat) for about 10 minutes, and then reconnecting it, but if that doesn't work, you will probably have to replace the module.

Try what Wyatt says ..put key in ignition . turn to on position for about 15 min. Turn ignition to off (not lock). then turn on and start. This will override the theft ignition system , and maybe allow the system to reset itself. let the car run for about 10 min

latch mechanism is probably motorized. Gently pushing the trunk lid down slides the lid/latch bar into the mechanism. this pushes a tab inside the motorized latch and the drive motor pulls the lid down tight and secure. you may be able to test the latch mechanism by sliding a pen or screwdriver into the latch groove to simulate the lid coming down. if you see the motor drive engage, and pull down the tool, you at least know this is working.

Please choose the correct steps for the size of engine that you have:

4.5L & 4.9L Engines

1. Drain the coolant to a level below the thermostat housing.
   
2. It may be necessary to remove the upper air filter assembly on some models.
   
3. Remove the 2 bolts securing the upper thermostat housing to the lower housing.
   
4. Remove the upper thermostat housing.
   
5. Remove the thermostat and O-ring from the lower housing.
   

Thermostat installation—4.5L and 4.9L engines

To install:

1. Install the thermostat and a new O-ring to the lower housing.
   
2. Install the upper thermostat housing to the lower housing. Tighten the thermostat housing bolts to 20 ft. lbs. (27 Nm).
   
3. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
   
4. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.
   

4.6L Engines

1. Drain the coolant to a level below the thermostat housing.
   
2. On some vehicles, access is easier if the front-end beauty panel and the air cleaner are removed.
   
3. Remove the 2 bolts securing the thermostat housing to the intake manifold.
   
4. Remove the thermostat housing.
   
5. Remove the thermostat and O-ring from the housing.
   

Thermostat installation—4.6L Engine



Loosen the upper radiator hose clamp at the thermostat housing



Remove the upper radiator hose clamp from the thermostat housing



Remove the thermostat housing retaining bolts and . . .






. . . remove the thermostat housing from the engine



Separate the thermostat from the housing

To install:

1. Install the thermostat and new O-ring to the housing.
   
2. Install the thermostat housing to the intake manifold. Tighten the thermostat housing bolts to 18 ft. lbs. (25 Nm).
   
3. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
   
4. Install the air cleaner and beauty panel, if removed.
   
5. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.
   

Remove the power window switch module - use a 1/2" wide flat bladed tool to pry up on the rear edge. Then CAREFULLY push in to disengage the clip and pull up. Disconnect the electrical.Remove the trim panel - there are two screws under the the covers at the ends of the door handle, and one behind the inside opener handle cover. BE VERY CAREFULL not to damage these covers.Gently release the retainer tabs located all around the door panel, and lift up to remove..

You need to find out what is missing when it won't start , spark - ignition system or fuel pressure . No Start Diagnostic Basics EricTheCarGuy

Any check engine light or codes? My first thought would be tps or possibly fuel filter. As car builds up pressure a clogged filter would cause your symptom.

to check for leaks go to an accredited radiator shop and have a pressure test done --check that there are no air locks in the system the transmission could be the problem as the transmission oil cooler is in one of the radiator tanks when idling there is no torque in the transmission but when travelling the transmission is under load IT might be advisable to go to an accredited auto transmission shop have an oil change done and have the bands and clutch packs adjusted the pan has to come off to do that and if there is a problem in the transmission , there will be signs in the transmission pan

Park/Neutral Position Switch On LH of Transmission, near base of rear Engine Lift Hook Do you know what a Starter Enable Relay is ? Location Forward of LH front Strut Tower, near Engine Compartment Fuse/Relay Center Did you test the circuit or are you guessing that is the problem ? Do you even know how the starter circuit works ? When the ignition switch is turned to the START position and the gear selector is in PARK or NEUTRAL, battery voltage is supplied to the starter enable relay coil along the following pathway: From the BATT 2 fuse Through RED (342) To the ignition switch To YEL (5) To the PARK/NEUTRAL position switch To (YEL 1737) To the starter enable relay coil At the same time, a start request is sent by the PASS-Key® II input to the instrument panel cluster (IPC).If the IPC senses correct Pass-Key® II system resistance, the IPC then energizes the starter enable relay by grounding one side of the relay coil. (Refer to Section 8A-133 for PASS-Key® II circuit description.) Once the starter enable relay is energized, the normally open contacts close, completing the following circuit: • From the BATT1 fuse • Through RED (142) • To the closed relay contacts • To PPL (6) • To the starter solenoid