| Author | Message | ||
     Gus Moreno (Tepuy) New Member Username: Tepuy Post Number: 3 Registered: 01-2004 |
What are the ways to turn the Service engine light off? Thanks. Gus. | ||
| Richard Garza (Rgarza) Member Username: Rgarza Post Number: 52 Registered: 05-2003 |
What year is the car? Richard | ||
| Richard Garza (Rgarza) Member Username: Rgarza Post Number: 53 Registered: 05-2003 |
Gus, just checked your profile. I have the same year LR. You have to have the computer checked to see what code. Go to autozone and ask them to do it. They will do it for free. They are not allowed to reset but that is the only way to reset the light. But you can ask the guy to clear the code and light will come off. However, if there is a problem the light will just come back on again. Once you get the codes post them and you will be able to get more help. Richard | ||
| john kazeva (Jkazeva) New Member Username: Jkazeva Post Number: 11 Registered: 02-2004 |
the Malfunction Indicator Lamp (MIL) / Service Engine Soon (SES) (North American Spec-NAS) lamp is supplied with battery voltage from the instrument cluster. When the Electronic Control Module (ECM) detects a fault, it provides an earth path to illuminate the MIL. Below is a list of the items I found that will illuminate it: ##-#-##'s are the page numbers in the Bentley Disco series II manual (VDR 100090) [i have its AtlanticBritish.com item # in my other post about my mirror] ALL for V8: 17-2-9: per the On-Board Diagnostics (OBD) provided via the Engine Management ECM, the MIL (Malfunfunction Indicator Lamp) or SES (Service Engine Soon) in NAS (North Amercian Spec) light comes on if: fault detected in two engine cycles w/ ignition, fueling and exhaust systems cause an excessive increase in tailpipe emissions. these faults iclude: component failures, engine misfire, catalyst damage, catalyst efficiency, fuel evaporative loss and exhaust leaks. all discussed are NAS spec: 17-2-18 on evaporative emission control system fuel leak detection system (vacuum type): failure of the ECM-run fuel evap leak check illuminates SES lamp; 17-2-26 if ECM detects a fuel tank pressure sensor failure it will illuminate SES 17-2-19: on evaporative emission control system fuel leak detection system (positive pressure type): failure of the ECM-run fuel evap leak check illuminates SES lamp (17-2-44: this test is run after the vehicle shuts off); 17-2-23: on evaporative emission control system fuel leak detection system (positive pressure type): if the purge valve breaks or sticks open or closed, EVAP system ceases to function and the ECM causes SES light to be illuminated. 17-2-37: if the "upstream" or pre-catalytic converter (CAT)s' O2 sensors' response time for rich-to-lean and lean-to-rich switching as measured by the ECM is greater than the 200 millisecond threshold, the SES is illuminated; 17-2-38 and 17-2-39 SES turned on if ECM detects: -lambda ratio outside of operating band [17-2-11: air/fuel ratio: 14.7:1 is theoretical stoichiometric ratio that is the cleanest burn lambda is defined as "excess air factor" to illustrate deviation from the stoich. optimum: lambda=1 optimum, lambda>1: lean mix(>1.3, mix won't ignite), lambda<1: rich mixture. The V8 uses closed loop engine mgt. control to operate so lambda is as close to 1.0 as possible: http://www.sts.sae.org/membersonly/techinfo/servicetech/oxygen13-17.pdf - if heated O2 sensors' resistance (checked after reaching their operating temperature) is outside upper and lower threshold values, SES is illiuminated; - O2 sensors' response time for rich-to-lean and lean-to-rich switching as measured by the ECM grows over time. This "aging" of the upstream O2 sensors' is compensated for with the post-cat (downstream) O2 sensors. If this as-compensated switching time limit is exceeded, SES is illuminated; - CAT efficiency degradation as defined as a CAT's inability to store oxygen. This is measured by the comparison of the upstream and downstream O2 sensors' voltage values. During transient (changing) conditions of engine operation, if the upstream and downstream O2 Sensor voltage values "follow" each other wihout an amount of lag, or, at steady state, in three different engine operation scenarios, a close amplitude ratio between the upstream and downstream sensors exists, this shows the CAT's reduced effiency as evidenced by the CAT's inability to store O2 and this cause the SES to be illuminated. 18-2-14 CKP crankshaft speed and position sensor signal failure will illuminate SES continuously. - accompanying symptom is a lot of stalling also. [my wife's 86 bmw 325 had a position and separate crank speed sensor. when the position sensor failed due to a water leak into it, it also took out the car's $1,000 ECM (probably was a $2.00 diode on the sensor's $20.00 I/O card in the ECM)] 18-2-18 ECT Engine Coolant Temperature sensor failure will illuminate SES continuously. - accompanying symptom is hard starting hot, or cold; 18-2-26 TP Throttle Position sensor failure will illuminate SES continuously. 18-2-42 SES LAMP I/O the Malfunction Indicator Lamp (MIL) / SES (NAS spec) lamp is supplied with battery voltage from the instrument cluster. When the ECM detects a fault, it provides an earth path to illuminate the MIL. Output to the MIL is via pin 20 of connector C0637 of the ECM. The ECM is located behind the right underdash kick panel snuggled under the "A" pillar (right body pillar that forms the right front door front frame). 18-2-49 "On vehicles fitted with an Automatic Transmission (AT), the ECM combines with the Electronic Automatic Transmission (EAT) Electronic Control Unit (ECU) to provide OBD strategy." 18-2-52 If Vehicle Speed Signal (VSS) fails, MIL/SES will illuminate: VSS, on AT vehicles, is used by the ECM to control idle speed and overrun cutoff. It is comprised of: 1) a hard wire input connection from the Self-Leveling/ABS (SLABS) ECU of a Pulse Width Modulated (PVM) signal consisting of 8000 pulses per mile, so it's frequency changes with road speed (zero mph/kph is a 2 Hertz reference), and 2) the AT output shaft speed (signal conditioned) from the EAT ECU. 18-2-55 Controller Area Network (CAN): a twisted wire pair between the ECM and the EAT ECU: Failure of this can illuminate MIL. - other symptoms are: AT hard shifting, or drives in 3rd gear only 44-19 while ignition is on, EAT ECU moniters for faults. - If it finds an AT fault that may impact emissions, it will illuminate the MIL/SES. 44-20 torque converter lock-up clutch fault will illuminate the MIL/SES, may affect driveability. EEPROM or watchdog fault (=> Emissions OBD II relevant) will illuminate the MIL/SES, w/o apparent driveability effects. 44-21 AT High/Low signal with implausible input will illuminate the MIL/SES, w/o apparent driveability effects. Sport/Manual warning lamp failure or Always ON will illuminate the MIL/SES, w/o apparent driveability effects. Some CAN error messages will illuminate the MIL/SES, w/apparent slight driveability effects. Altitude Shift control invalid message will illuminate the MIL/SES, w/apparent slight driveability effects. A much more severe symptom called AT "limp home" mode would kick in due to various AT anomalies and the MIL would also illuminate. that's all I found. |
