confused overheating

[jmos6969]

OK I have a 96 cad SLS with a overheating problem and a problem with it shutting off when I'm in drive at a lite or I'm not applying gas to car! Now it does not shut off when I'm in park or neutral. Now it turns back on when I start car back up with no problem but as soon as I slow down or come to a stop it turns off, but if I put in neutral or in drive while at a lite it keeps running yes I'm confused. so can the fuel filter make this happen?

Now I changed water pump and thermostat, and hoses. There are no leaks so I'm at my wits end right now

Please help.

[99EldoETC]

For overheating I know its recommended that you do a coolant test:

The shutting off at stop in drive, hopefully is a fuse. PCM comes to mind.TCC maybe too. How is your transmission? Are you getting any codes? Post them here but first look on CadillacJim profile for the link to the webpage he prepared with codes and their meanings.

[jmos6969]

I have no codes! Check engine lite do not come on.

[Cadillac Jim]

You can have OBD codes that do not turn on warning lights. Run the OBD codes as per the link in my signature block, write them down, and post them here.

[KHE]

Now I changed water pump and thermostat, and hoses. There are no leaks so I'm at my wits end right now

Please help.

Now that you have thrown those parts at the problem un-necessarily whout sucess, I suggest you test the coolant for combusion gasses to identify the problem.

[jmos6969]

Thank you very much for the help. I will do

[jmos6969]

Question my 96 SLS will not turn over power is coming from batt, but its not turning over. no revving no nothing no kick over not one darn thing. Plz help fuses look ok

[Cadillac Jim]

Turn on the key, and on the A/C buttons press <Off> and <Pass Warmer> together for a few seconds until all the dash lights come on like you just turned on the key, then release both buttons. The OBD codes will then be listed one at a time on the DIC. Write them down. The list will end with a prompt "PCM?" at which time you can press <Off> to re-run the codes and check your list and get any that you missed. When you are done, turn off the key.

The OBD codes will tell likely why the starter is not getting juice. With just an online message and no OBD codes, there are too many possibilities. You can run the codes in a few seconds for free.

[jmos6969]

OK here are the codes that came up.

Tc 0027, 0073

Rs 0063

PC 0603

Ir 2255

IP 1552,Pz 1552

Ac 1314

Please help.

[Cadillac Jim]

P0027 Exhaust Valve Control solenoid Circuit Range/Performance Bank 1

B0073 Supplemental Deployment Loop #1 Resistance Low
C0073 Delivered Driving Torque
P0073 Ambient Air Temperature Sensor Circuit High Input

P0063 HO2S Heater Control Circuit Low (Bank 2 Sensor 3)

P0603 Control Module Long Term Memory Reset

B2255 Generic Loss of Serial Data (Source ID Unknown)

B1552 Keep Alive Memory (KAM) Error

B1314 Evaporator Inlet Temp Sensor Open Circuit

The first code doesn't look like a TC code. The second one is probably C0073 if it is a TCS code.

The only thing that looks like it could cause a no-start condition is the B2255. But, it's thrown by the IRC, which is the radio. Thus it probably just means that the radio is disconnected or the fuse is out.

If you have a no-starter-response condition with no codes that reflect the problem, then it's probably the battery cable to the starter, the starter solenoid, or possibly the ignition switch. At this point you need to figure out if the starter solenoid is clicking. You probably can't hear it from the driver's seat. Try it when things are quiet, with the hood up and the window down, or someone listening under the hood. If it's not clicking, then it's time to pull the intake manifold and check to see if power is getting to the starter solenoid actuator coil.

[jmos6969]

Thank you very much that's what thought I was hopping I didn't have to do this, but thank u very much I will let you know the out come.

[jmos6969]

OK I took out starter went had it checked out at auto zone starter passes. And I don't thinks its my inition switch because I put a new in already. But its not doing anything power is going to car I can see that,but its not cranking at all no sound no turn over no nothing.

[Cadillac Jim]

Whatever happened to checking to see if there was power to the starter solenoid actuation terminal?

[Texas Jim]

Have you put it in NEUTRAL to see if it will start there???

[jmos6969]

OK I tried light testing all wires fuse, relays they seem OK . starter is fine alternator is fine I just don't know.

[jmos6969]

Yes I did try putting it neutral no go.

[Cadillac Jim]

The starter circuitry in the 1996 Northstar is very simple. But, you can't expect to read a message on the Internet, pick up a toolbox, and go fix the car. It just does not follow that you can fix the car without diagnosing the problem. Because something "looks like" it could be the problem is not sufficient cause to replace an expensive part without checking it out first.

I'm working on the assumption that the engine doesn't turn over and the solenoid doesn't click when you turn the key to START. Please take the time to make some measurements and look at some things and get back with us before you buy any more parts and wrench on the car.

The starter circuit is in the 1997 FSM page 6-203. There are two circuits, the starter enabling and switching circuit and the starter motor circuit. They are connected by the Starter Enable Relay.

The starter motor circuit is very simple. You have the battery, with one red (positive) cable going to the starter solenoid and one black (negative) cable going to the engine block. Make sure that both cables are OK, the terminals are clean, and the connections are good (a bad ground to the engine block will cause your problem). There is a starter solenoid actuator terminal on the solenoid. When voltage is applied to it, the solenoid pulls in and the starter motor runs, turning over the engine. The first thing that I asked you to check was whether there is voltage on the starter solenoid actuator terminal. It's the one with the PPL wire. If you have voltage there when you turn the key on but the starter doesn't turn over or the solenoid doesn't click, then the problem is with the starter or solenoid. If there is no voltage, then the problem is with the relay or the actuator circuit.

There is one Maxifuse involved, the BATT 1 50 Amp Maxifuse. That fuse powers the contacts on the starter enable relay which switches power to the starter solenoid actuator terminal.

The actuator circuit has a lot of things in it and any one of them can prevent the solenoid actuator coil from getting voltage. You can check them easily enough with an inexpensive voltmeter from Radio Shack, most hardware stores, auto parts stores, etc. A test lamp will do for most tests here.

The actuator circuit is powered through the 30 Amp BATT2 fuse. Power from that fuse goes to the ignition switch, which, when the key is turned to START, passes power to the Park/Neutral Position (PNP) Switch. The shifter must be in Park or Neutral for power to be passed on. The PNP must be plugged into the wiring harness and properly aligned. A maladjusted PNP switch is a very good candidate for your problem. You can try holding the key in START and moving the shifter slightly while in Park or Neutral and see if the solenoid clicks or the car starts; if it does' the PNP switch needs adjusting. Power from the PNP switch goes to the Starter Enable Relay coil.

The Starter Enable Relay coil is grounded through the Instrument Panel Cluster (IPC). The IPC will not enable starting the car unless the theft protection is working and is satisfied. If you are getting message on the DIC like "Wait 30 seconds" and such, there is a problem with the key or ignition circuitry that activates theft prevention.

The first thing to do is to try jiggling the shifter with the key in START and see if you can get the solenoid to click or the car to start. If that doesn't work, then you need to go through the actuator circuit to see where the problem is. You can start by using a voltmeter or test light to see if you are getting battery voltage to the starter actuator, the PPL wire on the solenoid. If so, you can look at the solenoid; you've already replaced the starter. If not, one of these things is the problem:

• The Starter Enable Relay.
• The 30 Amp BATT 2 fuse.
• The ignition switch isn't passing power to the starter circuit. Often this is a connector problem, not a switch problem. The electrical part of the ignition switch isn't in the steering column but is an assembly under the dash on the top of the steering column.
• The PNP switch isn't passing power to the Starter Enable Relay. This can be due to a bad connector, a mis-adjusted switch, or a bad switch. The YEL wires on the PNP connector are the input and output of the PNP switch.
• The PNP relay is sticking, the coil is open, or the contacts have gone bad.
• The IPC isn't grounding the Starter Enable Relay coil. This usually means that something is wrong in the theft prevention system.

The Starter Enable Relay is the big relay standing alone in the engine compartment fuse/relay center, on the fender side. You can use a voltmeter on its terminals to see whether power is getting to it, the IPM is grounding the coil, and power is being passed to the solenoid actuator coil. The wire colors are:

• YEL - power from the PNP switch (terminal F). Should be 0 Volts unless the key is in the START position, then should be 12 Volts.
• YEL/BLK - ground from the IPC (terminal D). Be careful with this wire because the IPC is static-sensitive and very expensive to replace. It should be 0 Volts if the key is in the ignition, even when the key is turned to START. Reading a volt or two is OK, but 12 Volts is not OK.
• RED - power from the 50 Amp BATT 1 fuse (terminal B ). This terminal should always have 12 Volts on it.
• PPL - output to the starter solenoid actuator coil (terminal E). This should have 0 Volts on it unless the key is in START and the shifter is in Park or Neutral; it goes to 12 Volts to start the car.

There is an unused terminal in the Starter Enable Relay, terminal C. This should read the same voltage as the PPL wire, and you can use it to see if the starter actuation circuit is working. The relay terminals are numbered A-F from right to left. Terminals A and C are not used (terminal A is not connected) and the wire colors can help you sort out which is which.

If you are having a problem with the theft prevention or the IPC is not grounding the Starter Enable Relay, then you *will* have OBD codes that tell what is happening and why. If you have no OBD codes that relate to the starting problem, then you can ignore the YEL/BLK wire on the relay.

Do some testing and come back with questions and results of your testing. We can nail this.

[jmos6969]

Please is there anyone out there that can help me.

[Cadillac Jim]

Please is there anyone out there that can help me.

Two simple things:

• Put the car in Neutral and try to start it while moving the shifter back and forth a little; if the solenoid clicks or the car starts, adjust the Park-Neutral switch.
• If that doesn't help, get a voltmeter (they start at about $15) or a test light and see if you are getting power to the Starter Enable Relay at the PPL wire or terminal C (the unused one two from the right end of the relay). If it is getting power when you turn the key to START, it's the solenoid. If it's not, report back here with your OBD codes for the next step.

[Cadillac Jim]

Here is the 1997 FSM page with the schematic of the starting circuit. The 1996 should be identical.

[jmos6969]

Good morning Cadillac Jim I just want to let you know I'm very thankful for your help. OK do you think it could be my security system? Because I did a test on it. I turned on security then open door but system did not go off is there any way I can test this out.

[jmos6969]

Anyone have any video to show me how to bypass my system?

[Cadillac Jim]

Bypassing the security system is a nightmare. If they made it easy, they just as well might have left it off the car. But, it rarely gives any trouble and is easy to fix. The most common problem with it is bad contacts with the resistor in the key, which is usually fixed by getting a new key at an Ace Hardware or other shop that makes keys for cars with theft-prevention pellets.

If the theft prevention system is the problem, you will have messages on the DIC and you will have OBD codes. If the DIC doesn't say anything, you need to look at the PNP switch, the Starter Enable Relay, and the ignition switch.

But you really should get a voltmeter or at least a test light and check things out in the car. You can find the problem in a few minutes that way without turning a wrench.

The Starter Enable Relay is easy to get to. There is a cover over the Underhood Fuse/Relay Center and Maxifuse Blocks. It's in front of the left strut tower. You will have to work the cover out from under a cable to the cruise control but it's easy to get off an on. Here's the FSM page showing where it is:

Here's the end view of the relay connections (I believe that the wiring harness connector is the mirror image of this). Ignore the "DOOR LOCK RELAY." That's just what the parts vendor calls it. I suppose that the same part is used as a door lock relay too.

Note that you can look at the schematic in the previous post, find the relay from the picture, and locate and identify the wires in the Starter Enable Relay by the wire colors and the fact that terminals A and C aren't used. You can put a test light on the PPL wire on Terminal E, which is the next-to-last one on the left, and if it doesn't light up when you turn the key to START then the problem is to the left of the relay in the schematic. If the test light does light up, the problem is to the right of the relay, and is probably the solenoid, because you already had the starter tested and have checked out the fuses, battery, and battery cables and ground.

[jmos6969]

Good afternoon just want to say thank you for all the good info its helped, but its still not starting. I have a question I just checked my maxi fuses all of them and I'm not get no light on my tester when the car is on honor when its off plz help! Now can this be my PCM?

Now the car was starting up fine out side of the over heating problem the car ran fine.

[Cadillac Jim]

The PCM very rarely goes bad. You can pop *all* the modules in your car by hooking up jumpers backwards with a dead battery, or putting a fast charger (24 Volts or some such) on a battery in the car without disconnecting it, and it's possible to break anything if you really try. But I've never heard of a Northstar PCM going bad in a car by itself.

To use a test light, you must connect one of the two wires to a good ground, like a piece of metal on the engine or a bolt on the body. Then, if the other wire is connected to something with battery voltage, it will light up.

If you are getting no power to the Maxifuse block, check the battery cable positive connector. Take it off the battery and pry all three terminals out of it and clean them, and clean between them. If they battery cable doesn't go back tight, get a copper washer from the auto parts store to tighten it up.

One of the three big red cables goes across the car at the bottom of the radiator to the Maxifuse block and powers the car. Another goes to the alternator and the third goes to the starter solenoid.