2001 Cadillac Deville Emissions

Tiny
STELLAKI
  • MEMBER
  • 2001 CADILLAC DEVILLE
Engine Mechanical problem
2001 Cadillac Deville Front Wheel Drive Automatic 250000 miles

I have Cadillac DeVille that will not pass emissions. The computer has been changed twice, as well as the Catalytic converter once. Cadillac is saying that the car should pass, but it's the computer codes that are not resetting. I read in a previous posting that when the codes are reset, the E/M is goes to an "unready" status. Can this be causing the problem? If not, what else can we do to get the car through inspection as it's used for a business car and will not be able to be used at the end of the month. Thanks so much.
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No
Tuesday, July 20th, 2010 AT 9:45 AM

3 Replies

Tiny
FACTORYJACK
  • EXPERT
It is correct that after a clear codes command is issued, the I/M status' go 'unready'. It should not take too long for the tests to run and change to ready. If there is a fault storing, it may not change to ready status. An obvious fault will illuminate the check engine light, most often on the second time it runs and fails a given test. But it will store a first failure in record, and this may prevent some tests from running. Is there a check engine light, and are there any codes?
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Tuesday, July 20th, 2010 AT 10:55 PM
Tiny
STELLAKI
  • MEMBER
No, there's no check engine light on and as far as I know, no codes are reflected. We had two new computers installed in the last year and when we took the car to Cadillac, they said that a new computer was needed. It's getting to the point of rediculous. The car is running beautifully and there is no problem with the emissions except for this computer issue.
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Wednesday, July 21st, 2010 AT 5:30 AM
Tiny
FACTORYJACK
  • EXPERT
Here is the procedures that the dealer should have referenced, instead of replacing engine control modules. The info is taken from GM service information, specific to your vehicle. If there is a specific I/M that is not indicating yes, reference that in your reply.

Inspection/Maintenance System Check
Description
Several states require that a vehicle pass on-board diagnostic (OBD) system tests and the I/M emission inspection in order to renew license plates. This is accomplished by viewing the I/M System Status display on a scan tool. Using a scan tool, the technician can observe the I/M System Status in order to verify that the vehicle meets the criteria that complies with the local area requirements.

Conditions for Updating the I/M System Status
Each system requires at least one, and sometimes several, diagnostic tests. The results of these tests are reported by a diagnostic trouble code (DTC). A system monitor is complete when either all of the DTCs comprising the monitor have Run and Passed, or any one of the DTCs comprising the monitor have illuminated the MIL. Once all of the tests are completed, the I/M System Status display will indicate YES in the Completed column. For example, when the HO2S heater test indicates YES, all of the oxygen sensor heaters have been diagnosed. If the vehicle has four heated oxygen sensors, all four heater circuits have been diagnosed. The I/M System Status will indicate NO under the Completed column when any of the required tests for that system have not run. The following is a list of conditions that would set the I/M System Status indicator to NO:

" The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the tests.

" The battery has been disconnected or discharged below operating voltage.

" The control module power or ground has been interrupted.

" The control module has been reprogrammed.

" The control module DTCs have been cleared as part of a service procedure.

Monitored Emission Control Systems
The OBD II system monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. For example, a vehicle may not be equipped with AIR or EGR. The OBD II regulations require monitoring of the following:

" The air conditioning system

" The catalytic converter efficiency

" The comprehensive component monitoring -- Emission related inputs and outputs

" The evaporative emissions (EVAP) system

" The exhaust gas recirculation (EGR) system

" The fuel delivery system

" The heated catalyst monitoring

" Misfire monitoring

" The oxygen sensor system (O2S or HO2S)

" The oxygen sensor heater system (HO2S heater)

" The secondary air injection (AIR) system

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table. Systems such as fuel delivery, misfire, and comprehensive components may not be listed in a System Status list. These tests run continuously on some vehicles and may not require an indicator.

Diagnostic Aids
The I/M System Status display provides an indication of when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, the failure may prevent other required tests from running. For example, a DTC for the control circuit of the relay controlling an AIR pump may not be listed in the Inspection/Maintenance System DTC Table because the DTC is a continuous test. If this DTC is set, the Active Tests for the AIR system may not run.

The I/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

Any DTCs set, even those that are not listed in the Inspection/Maintenance System DTC table, may prevent the required DTCs from running. If there is any question as to whether a set DTC is disabling the required I/M diagnostic, review the Conditions for Running in the diagnostic procedures for the DTC required by the I/M diagnostic. A list of disabling DTCs, if applicable, is contained in the supporting text for that DTC.

Anytime a control module is reprogrammed or the diagnostic trouble codes are cleared as part of a repair procedure, all the I/M System Status indicators will reset to NO.

Use discretion when determining whether the entire system set procedure needs to be performed. For example, if the only tests that have not run are those that require the engine to be at operating temperature, then only those individual tests need to be run. There is no need to allow the engine to completely cool in order to run these tests.

Step
Action
Yes
No

1
Perform Diagnostic System Check - Engine Controls
Important: Many DTC related repairs will instruct the technician to clear the DTC information. This procedure will reset ALL of the I/M System Status indicators to NO, and require performing the I/M Complete System Set Procedure.

Repair any DTCs or driveability concerns that would prevent the I/M System Status tests from completing.
Did you find and repair a DTC or driveability concern?
Go to Step 3
Go to Step 2

2
Review any service bulletins for software updates that may prevent I/M readiness.
Perform any reprogramming or repairs indicated by the service bulletins.
Was a reprogramming or repair service required?
Go to Inspection/Maintenance (I/M) Complete System Set Procedure
Go to Step 3

3
With a scan tool, observe the I/M System Status display.

Is more than one test indicating a NO status?
Go to Inspection/Maintenance (I/M) Complete System Set Procedure
" Inspection/Maintenance Secondary Air Injection System Set

" Inspection/Maintenance (I/M) Catalyst System Set Procedure

" Inspection/Maintenance (I/M) Exhaust Gas Recirculation (EGR) System Set Procedure

" Inspection/Maintenance Evaporative Emission System Set

" Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor System Set

" Inspection/Maintenance Heated Oxygen Sensor Heater System Set

Inspection/Maintenance Complete System Set Procedure
Description
The purpose of the I/M Complete System Set Procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics, and complete the trips for those particular diagnostics. When all diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform this test when more than one or all of the I/M System Status indicators are set to NO.

Conditions for Running
" The barometric pressure is more than 72 kPa.

" The engine coolant temperature (ECT) is between 5-120 C (41-248 F).

" The intake air temperature (IAT) is between -6 to +200 C (21-392 F).

" The battery voltage is between 9-18 volts.

" The fuel level is between and .

Diagnostic Aids
Rough road conditions may prevent some of the tests from running. Extreme high or low ambient temperatures may prevent tests such as HO2S heater and EVAP system from initiating. If a step is interrupted before completion, perform the remaining portion of the set procedures. Any portion of the set procedure that requires the engine at operating temperature may be repeated. This allows most of the diagnostics to run and the remaining tests can be performed using the individual System Set Procedures.

If the vehicle has recently run, start this procedure at step 3. This will allow the tests that require the engine at operating temperature to run. Using this method allows shorter cool down periods if the tests requiring a cold start do not initiate.

The scan tool can be used to monitor each of the I/M System Status indicators during the I/M Complete System Set Procedure. When all of the indicators for a test step have updated to YES, testing can move on to the next step even if the remaining portion of the test is not complete. For example, step 3 is designed to run the EVAP, AIR, and HO2S tests. The procedure instructs the technician to operate the vehicle in the enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, the enable conditions do not need to continue, and testing can advance to the next step.

Test Description
The numbers below refer to the step numbers on the diagnostic table.

Make sure you perform the I/M System Check before performing this test. Failure to do so may result in difficulty updating the status to YES.

This step is to run the HO2S heater tests and initiate the EVAP System Test.

Preprogramming the scan tool will reduce the amount of time the oxygen sensor heaters operate while verifying the enable criteria.

This step is to run the EVAP, AIR and the Oxygen Sensor Tests. The EVAP Test begins once the engine coolant reaches a calibrated temperature. The AIR Test, if equipped, begins shortly after Closed Loop and the indicated speed is achieved. The Oxygen Sensor Tests begin once the engine is at operating temperature, in Closed Loop Fuel Control, and a calibrated amount of time has elapsed.

This step is to run the EGR Tests. The EGR Tests are run during a gradual deceleration with a closed throttle. The vehicle speed is required in order to maintain a high, steady MAP signal.

This step is to run the Catalyst Tests. This test runs during the idle period immediately following a cruise period that meets a minimum calibrated RPM and time period.

Perform the individual system test for any of the systems that do not update to YES.

The I/M System Status only reports on whether or not a diagnostic has run, not the outcome of the test. If any emission related DTC sets after the tests are complete, the DTC will require diagnosis.

Step
Action
Value(s)
Yes
No

1
Did you perform the Inspection/Maintenance (I/M) System Check?
--
Go to Step 2
Go to Inspection/Maintenance (I/M) System Check

2
Important: Whenever the ignition is turned ON, ignition positive voltage is supplied to the HO2S heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure.

Preprogram the scan tool with the vehicle information before the ignition is turned ON.
Ensure the vehicle is within the Conditions for Running specified in the supporting text.
Turn OFF all of the accessories, e.G, A/C, blower fan, etc.
Set the vehicle parking brake.
Verify the transmission is in Park for automatic transmissions and Neutral for manual transmissions.
Start the engine and allow it to idle.
Allow the engine to idle for the specified time.
Is the action complete?
2 minutes
Go to Step 3
--

3
Caution: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

In order for the next group of tests to run, the vehicle must operate in the following conditions:

Acceleration at part throttle to 90 km/h (55 mph) with this speed maintained until the engine reaches operating temperature. This may be up to 8-10 minutes depending on the start up coolant temperature.
Continued operation under these conditions for an additional 6 minutes.
Is the action complete?
--
Go to Step 4
--

4
Caution: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

In order for the next group of tests to run, the vehicle must operate in the following conditions:

Vehicle speed reduced to 72 km/h (45 mph) with this speed maintained for one additional minute.
Four decelerations of 25 seconds each from 72 km/h (45 mph) while the following criteria is maintained:
" Throttle is closed

" NO brake application on either manual or automatic transmission

" NO clutch actuation on a manual transmission

" NO manual downshift

" Vehicle speed remains above 40 km/h (25 mph)

" After each deceleration period, vehicle is returned to 72 km/h (45 mph) under part throttle acceleration and speed is maintained for 15 seconds.

Is the action complete?
--
Go to Step 5
--

5
Caution: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

In order for the next group of tests to run, the vehicle must operate in the following conditions:

Acceleration at part throttle to 75-89 km/h (45-55 mph) with this speed maintained for 2 minutes.
Deceleration to 0 km/h (0 mph).
Engine idling for 2 minutes while the following criteria is maintained:
" Service brake depressed

" Automatic transmission in drive

" Manual transmission in neutral with the clutch pedal depressed

Is the action complete?
--
Go to Step 6
--

6
With a scan tool, observe the I/M System Status display.

Did all of the I/M System Status indicators update to YES?
--
Go to Step 7
" Inspection/Maintenance Secondary Air Injection System Set

" Inspection/Maintenance (I/M) Catalyst System Set Procedure

" Inspection/Maintenance (I/M) Exhaust Gas Recirculation (EGR) System Set Procedure

" Inspection/Maintenance Evaporative Emission System Set

" Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor System Set

" Inspection/Maintenance Heated Oxygen Sensor Heater System Set

7
With a scan tool, observe the Emission Related DTC portion of the I/M System Status display.

Does the scan tool indicate any Emission Related DTCs set?
--
Go to Inspection/Maintenance (I/M) System DTC Table
System OK
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Wednesday, July 21st, 2010 AT 10:22 PM

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