Question about 2007 Cadillac CTS 3.6L

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Re-manufactured ECM, programmed locally, new alternator, new battery. Intermittent but persistent problems. Symptoms of bad ECM still. Could it be a relearn issue or ECM still no good

I have a Cadillac CTS 2007 that has been acting strange. The first time the key was stuck and security light came on. Later that day the car wouldn't start, husband disconnected battery and reconnected. We then took the car to auto parts store and they checked the battery since all codes were cleared. Battery was dead. Replaced battery and everything was normal for two weeks. Then it started all over again with same symptoms and the traction control light would stay on. Then the radio would stop working, gas gauge would go to zero, temperature gauge would go to zero, traction control light and the a/c would go hot. These would intermittently happen. Sometimes the key would come out and others it wouldn't. Sometimes the theftlock would come on the DIC and others the check security system would come on the DIC. A few times it wouldn't start. Once it started and when we pressed the gas it wouldn't rev the engine. Took it to a garage and had it checked while it was giving all the warnings and check engine light was on. Come back as bad ecm. The mechanic attempted to remove my key and get my accessory lights off but it wouldn't work. For almost two hours we tried to disconnect battery, reconnect battery, disconnect and reconnect the ECM, checked fuses, etc. Still couldn't get the key out or accessory lights off. Finally we were able to and found the battery was dead and they suggested to also replace the alternator since the battery was new. Replaced the alternator and two days later the problems returned. Ordered a re manufactured ECM. Finally took it to dealer, husband installed new ECM in the parking lot and we left it to get it programmed. Went to get the vehicle, drove home less than five miles from shop. Parked it for several hours and tried to lock the car with the interior door locks; didn't work, tried the key fob; didn't work. Called the shop. While on the phone tried key fob again; nothing. Went to car and tried interior door locks;nothing, tried trunk button from inside the car; nothing. Then all of a sudden trunk opens and security alarm goes off. Attempt to install key to turn it off and car wouldn't do anything. Finally car starts but traction control light was on and the security light. Turn car off and attempt to lock it with plans to return to shop the next morning. That afternoon ran out to pick my DS up from work and all previous symptoms were back along with intermittent THEFTLOCK and service theft system warnings on DIC. Decided to stop at parts store and get codes scanned. Nothing. Turn car off and attempt to remove key; didn't work. After restarting the car and waiting a few seconds the THEFTLOCK went off the DIC and I was able to remove key. Tried to lock the doors; nothing. Spoke with the guy who took codes but there was none showing. Decided to test my key fob. When I tested my key fob my car locks. From INSIDE the store. Same key fob that hasn't been working since getting it back from the store and that has never worked from inside of a store. Take my car home and park overnight. Take my DD to school this morning and everything was fine. Key fob good, no warning lights, interior door locks ok and the trunk buttons working, etc. Drive around some to see if it happens again and it doesn't. Several hours pass as I am trying to decide what to do about going back to dealership. Hoping that it was a badly programmed ECM and that I don't have to spend out a ton of money. Get ready to go to the store and suddenly everything has returned. Attempt to roll down windows and open sunroof and those aren't working either. I haven't tried opening sunroof during past times but windows don't work during certain times in the past. Any ideas on what in the world is going on? Maybe I just need an exorcism done on my possessed car?! So far we are at about $1100 and that is with my husband doing the work except for the ECM programming. My car has been out of commission over 2 weeks now. I really need it back ASAP and cheaply. We plan to sell it as soon as we get things ironed out with it.

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2007 Cadillac CTS 3.7 theftlock shut off fuel pump and won’t start . Disconnected the negative cable to reset ECM and will not crank over now . Theftlock still on .

Posted on Oct 16, 2018

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Well now that some problem ! The problem with going to the parts store to have codes checked is they only check PCM - engine computer codes . Your vehicle has more then just the PCM/ECM
?€¢
The instrument panel cluster (IPC)


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The engine/powertrain control module (ECM/PCM)


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The electronic brake control module (EBCM)


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The HVAC control module


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The radio


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The dash integration module (DIM)


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The rear integration module (RIM)


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SP303


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The inflatable restraint sensing and diagnostic module (SDM
All These modules share information on the class 2 serial data bus any one of these modules could have a lose or bad ground causing these problems !
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Scan tool power battery positive voltage at terminal 16.


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Scan tool power ground at terminal 4.


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Common signal ground at terminal 5.


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Class 2 serial data at terminal 2.


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Keyword serial data at terminal 7, w/TR7.


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High Speed GMLAN (+) serial data at terminal 6, w/LY7 or LP1.


?€¢
High Speed GMLAN (-) serial data at terminal 14, w/LY7 or LP1.

The serial data circuits are the means by which the control modules on the vehicle communicate with each other and the scan tool. There are 3 different types of protocols on this vehicle.
?€¢
The class 2 serial data


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The keyword 2000 serial data


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The high speed GMLAN serial data

The scan tool will power up with the ignition off. Some modules however, will not communicate unless the ignition is on and the power mode master (PMM) module sends the appropriate power mode message. Refer to Body Control System Description and Operation for operation of the PMM.
Class 2 Serial Data
The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. This serial data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each other. Once the scan tool is connected to the class 2 serial data line through the DLC, the scan tool can be used to monitor each module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). Class 2 serial data is transmitted on a single wire at an average of 10.4 kbps. This value is an average, class 2 uses a variable pulse width modulation to carry data and depending on the message it may operate faster or slower. The bus will float at a nominal 7.0 volts during normal operation. Each module can pull this lower during the transmission. The bus is not at battery positive voltage or ground potential during normal operation. When the ignition switch is in RUN, each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating, for example, when the inflatable restraint sensing and diagnostic module (SDM) SOH message disappears, several modules set DTC U1088. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.
You need to have all the modules on the vehicle checked an you need to take your vehicle to a qualified repair shop . You blame the PCM/ECM , I don't think so , sounds like a bad ground . Windows an locks not working are not part of the ECM/PCM . There are modules inside the doors.
Each door lock actuator is powered and controlled by the door module mounted in the individual door, but the rear integration module (RIM), which is the master control for the door lock system, determines when the lock functions are permitted. The RIM receives and examines lock function requests from the individual door modules, or from the remote function actuator (RFA) via the class 2 serial data circuit. The RIM also examines the transmission shift selector position and the ignition switch position information available over the class 2 serial data circuits. If the RIM determines that all conditions are correct for a lock or unlock function to be permitted, it sends a class 2 message back to the individual door modules commanding them to perform the lock or unlock function requested.
Your vehicle also has
Electronic Park Lock Description and Operation
If the vehicle is equipped with automatic transmission and a floor mounted console gear shift, it has an electronic park lock system (EPL). The EPL system purpose is to prevent the ignition key from being turned to the OFF position when the transmission is in any position other than PARK and the vehicle may still be moving. The EPL system consists of an ignition lock cylinder solenoid, and a park position switch that is located in the A/T shift lock control switch. The ignition lock cylinder solenoid contains a pin that is spring loaded to mechanically prevent the ignition key cylinder from being turned to the lock position when the vehicle transmission is not in the PARK position. If vehicle power is lost, and/or the transmission is not in the Park position the operator will not be able to turn the ignition key to the lock position and will not be able to remove the ignition key from the column
Fail-safe Operation
Since the operation of the vehicle systems depends on the power mode, there is a fail-safe plan in place should the power mode master (PMM) fail to send a power mode message. The fail-safe plan covers those modules using exclusively serial data control of power mode as well as those modules with discrete ignition signal inputs.
Serial Data Messages
The modules that depend exclusively on serial data messages for power modes stay in the state dictated by the last valid PMM message until they can check for the engine run flag status on the serial data circuits. If the PMM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is True, indicating that the engine is running, the modules fail-safe to RUN. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is False, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.
Discrete Ignition Signals Those modules that have discrete ignition signal inputs also remain in the state dictated by the last valid PMM message received on the serial data circuits. They then check the state of their discrete ignition input to determine the current valid state. If the discrete ignition input is active, battery positive voltage, the modules will fail-safe to the RUN power mode. If the discrete ignition input is not active, open or 0 voltage, the modules will fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

Posted on Aug 31, 2016

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  • Cadillac Master
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You may have to take your rolling nightmare to a real mechanic to get it finally straightened out.

Posted on Aug 31, 2016

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1 Answer

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Tip

Intermittent Miss


If you have a vehicle that has an intermittent miss...it doesn't cost anything to check the positive battery terminal first; which 50% of the time...is most likely the problem.

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