Sae Combination
Functionality of Powertrain Control Module (PCM) in OBD II Diagnostics
Powertrain Control Module (PCM) performs the following functions in relation to
OBD II Diagnostics:
Perform micro-processor based self diagnostics to ensure correct operation of the PCM and safe storage of OBD II diagnostic data in memory.
Perform On-Board diagnostics in real time and alert the driver by illuminating MIL in case of a fault Perform powertrain control functions to reduce emissions and meet OBD II regulations during open-loop operation at start-up time.
Perform powertrain control functions to reduce emissions and meet OBD II regulations in closed-loop control during normal operation.
Perform microprocessor-based self diagnostics to ensure correct operation of the PCM and safe storage of OBD II diagnostic data in memory.
The PCM performs the following self diagnostics:
- Verify the checksum of the program memory in ROM with its function and correct version.
- Perform read and write test of RAM cells for fault free memory Perform processor functions in CPU, peripheral devices including A/D converters, watchdog timers, and registers to verify that the processor is functioning properly.
- Perform checks on stored vehicle data and verify that the data is not corrupted and is within reasonable limits of vehicle operation.
- Perform On-Board diagnostics in real time and alert the driver by illuminating MIL in case of a fault, by interspersing diagnostics with vehicle control functions.
The diagnostics are classified into priority levels from 1 to 8 or 9. The highest priority level tests are done every 1 millisecond, followed by next priority level tests every 5 milliseconds, 10 milliseconds, 20 milliseconds, 50 milliseconds, 100 milliseconds, 200 milliseconds, 500 milliseconds, and 1 second. The highest priority level tests are those that effect safety and emissions to a high degree according to OBD II regulations. These include Oxygen sensor (lambda sensor), and fuel trim checks during closed loop operation of the vehicle. The next priority checks are the interrupt timers, and watchdog timers. The next priority tests are sensors, including EGO sensor, Throttle position sensor, Misfire detection, MAP sensor, Engine RPM sensor, MAF sensor, Crankshaft position sensor, and Engine coolant sensor. The next priority tests are EGR intrusive tests, Catalytic converter’s secondary air, and canister purge, fuel level sensor, pedal actuator, and ignition timer. The next priority checks are periodic self tests.
The PCM performs on-board diagnostics in real time; The PCM is interrupted by the real time scheduler during the performance of its normal vehicle control functions when the on-board tests are due. At this time the PCM saves its current state of the vehicle and performs the diagnostics. This takes about 100 microseconds. Then the PCM returns to its normal vehicle control functions. This repeats for each priority level diagnostics. In this manner the PCM spends about 15-40% of its time to diagnostics and the rest to perform its normal vehicle control functions.
The method of testing each component depends on the electrical characteristics and vehicle functions performed by the device. The PCM maintains the low and high limits for each test parameter, and normal range of values and performance requirements for each component that it tests. The PCM also has adequate hardware test capability to find a short circuit, or open circuit, or the noise level of a signal, including battery, power supply, wiring harness, each sensor, actuator and control unit related to emissions control.
The PCM tests each sensor by measuring each test parameter, such as input, or output and comparing it with the expected value stored in the technical data for the sensor.
The PCM also compares the signals of the components under test with a combination of information provided by other sensors, to verify the reasonableness of values provided by the components. The noise level and the performance of each signal of the component is checked as well.
Actuators are tested similarly to the way the sensors are tested for short circuit, open circuit, and range and performance levels. The test method also includes computing a test output of a sensor using different engine parameters and comparing them for compliance. This is called analytical redundancy. The actuator under certain conditions is intrusively activated and its output is measured to verify against the expected value for proper operation. If discrepancies to the nominal values are diagnosed in any component under test, the information is stored in memory with all the relevant supporting data, such as engine speed, MAP sensor, coolant temperature, and others. This is called “Freeze Frame” since it gives the vehicle’s state at the instant of failure of that component.. Thus defects that appearance or under certain conditions can be diagnosed, if the fault occurs only once during several cycles, it is deleted.
The fault persists for two cycles consecutively; it is not erased until the defect is repaired by the technician. In case of an out of range output of a sensor, the PCM substitutes a corresponding reasonable value for that vehicle condition of operation. The PCM also provides clear information to the driver by illuminating the MIL (Malfunction Indicator Light) in case of a defect without causing alarm for minor problems. All relevant data for off-board diagnostics and repair are stored by the PCM in its memory for later use. In the case of a defect that completely impairs the vehicle performance the PCM has the full capability to switch the vehicle state to a safe state of lesser capability called “Limp Home” state, in which the vehicle is brought to a safe degraded operating condition that includes a halt of the vehicle.
The PCM communicates with the OBD II scan tool and provides diagnostic data, and OBD II DTCs of all faults experienced by the vehicle so far to the external tester to facilitate off-board diagnostics, and vehicle repair. In this respect OBD II provides SAE J 1850 data link for communication of diagnostic data, SAE J 2012 provides the DTC message formats, and SAE J 1979 provides the test modes, requesting PCM for emissions related powertrain diagnostics data.
About the Author
specialist in Automotive diagnostic scanner R&D engineer
http://www.micro-tronik.com
SAE Beat Lab Commercial
|
|
20pc. METRIC and SAE STUBBY COMBINATION WRENCH SET new $29.99 |
|
|
New kobalt 12 point 12 piece sae/metric combination wrench set short/stubby $44.99 |
|
|
PRO TRUCKER TOUGH 6pc 12-POINT SAE COMBINATION WRENCH SET ~NEW~ $4.99 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $11.69 |
|
|
20-PC Professional Combination Wrench Set Metric & SAE $19.99 |
|
|
Kobalt 7 Piece Multi-fit Combination Wrench Set SAE 0359485 NIP $33.99 |
|
|
Kobalt 11-Piece SAE Combination Wrench Set 338603 Model # 85550 STANDARD $39.92 |
|
|
CRAFTSMAN 8 PIECE SAE COMBINATION RATCHETING WRENCH SET ^ BRAND NEW POLISHED! $42.97 |
|
|
Neiko 20 pc Stubby Metric SAE Combination Wrench Set $29.69 |
|
|
Kobalt SAE 7 Piece Multi-fit 15 Degree Offset Combination Wrench Set #0359485 $21.99 |
|
|
O RATCHET26 PIECE SAE AND METRIC COMBO SOCKET SET WITH CASE COMPLETE $40.00 |
|
|
New Task Force 5 Piece SAE Combination Wrench Tool Mechanic Gift Set $5.99 |
|
|
14pc High Polished Combo Wrench Set SAE Auto Hand Tool Automotive Tools $49.95 |
|
|
CRAFTSMAN COMBINATION WRENCH SET SAE AND METRIC $29.01 |
|
|
Craftsman 10 Piece SAE Combo wrench set – 12 Point – BRAND NEW! $19.97 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $10.50 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $10.50 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $10.50 |
|
|
NEW Craftsman Fully Polished Combination Ratcheting Wrench Set (8 piece) (SAE) $34.00 |
|
|
28pc CRAFTSMAN 12-POINT COMBINATION WRENCH SET SAE / METRIC MIDGET IGNITION ~NEW $99.99 |
|
|
30pc Combo Hex Key Allen Wrench Set SAE/MM Hand Tools Wrenches Wholesale $14.95 |
|
|
7pc ORIGINAL GEARWRENCH PROFESSIONAL FLEX HEAD RATCHETING COMBINATION WRENCH SAE $64.99 |
|
|
New MIT 8 Piece SAE Combination Wrench Set 12-Point $9.50 |
|
|
PRO TRUCKER TOUGH 6pc 12-POINT SAE COMBINATION WRENCH SET ~NEW~ $4.99 |
|
|
New 11 Piece SAE Combination Box Wrench Set $8.99 |
|
|
New 11 Piece SAE Combination Box Wrench Set & 5 Piece Screwdriver Set $12.99 |
|
|
PROTO PROFESSIONAL 7 PIECE SAE COMBINATION WRENCH SET 3/8” TO 3¼” $22.50 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $10.50 |
|
|
NEW Craftsman Fully Polished Combination Ratcheting Wrench Set (8 piece) (SAE) $32.00 |
|
|
11 PC 6 Point SAE Combination Wrench Set to 1″ GRIP $27.75 |
|
|
Kobalt 7-Piece SAE Multifit Combination Wrench Set(NEW) $28.88 |
|
|
11pc SAE ANGLE HEAD COMBINATION WRENCH SET New Combo Wr $24.99 |
|
|
NEW Craftsman Fully Polished Combination Ratcheting Wrench Set (8 piece) (SAE) $24.50 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $10.50 |
|
|
VHT-94040 V8 Hand Tools Jumbo Long Pattern SAE Combo Wrench, 1-3/8″ $32.14 |
|
|
VHT-9414 V8 Hand Tools 14pc. Long Pattern SAE Combo Wrench Set $89.35 |
|
|
NEW 7 Piece SAE Ratcheting Combo Wrench Set $25.49 |
|
|
NEW 9 pc. SAE Highly Polished Combo Wrench Set $11.29 |
|
|
28pc SAE and METRIC COMBINATION WRENCH SET tool New $49.99 |
|
|
Craftsman 10pc Ignition Combination SAE Wrenches Set Wrench Tools USA Made $12.99 |
|
|
NEW JH WILLIAMS SAE OFFSET COMBINATION WRENCH SET 11990 $92.50 |
|
|
Used PROTO Professional KD & JD SAE Combo Wrench Set 3/8″ – 1-1/16 + 1-1/4″ $26.00 |
|
|
NEW Craftsman 8pc SAE Combination Flip Reverse Ratchet Wrench Set Standard 12pt $36.00 |
|
|
CRAFTSMAN 8 PIECE SAE POLISHED RATCHETING COMBO WRENCHES – BRAND NEW^ $42.97 |
|
|
14pc Allen SAE Long COMBINATION WRENCH SET Big 1-1/4″ Made by Allen Industrial $49.99 |
|
|
STANLEY 4 finish combination wrenches FULL POLISH 12 pt Sae Stamped chrome NEW $0.99 |
|
|
NEW Craftsman 6pc SAE/STD Standard HUGE Giant Combination Wrench Set 12pt $55.00 |
|
|
Craftsman 12 piece combination wrench set 6 sae and 6 metric $3.79 |
|
|
NWOP HUSKY ¼” inch combo 12 point box & open end SAE POLISHED wrench $2.00 |
|
|
NEW Craftsman 20pc SAE/STD Combination Wrench Set 6pt Standard $46.00 |
|
|
6pc. SAE JUMBO COMBINATION WRENCH SET upto 2″ tool new $59.99 |
|
|
(2) 6-Piece Combination Wrench Sets- (SAE) New-Vintage Taiwan Made $7.99 |
|
|
SAE SIZE GEAR HEAD COMBINATION RATCHET BOX END WRENCH RATCHETING END TOOL SET $109.99 |
|
|
S-K Hand Tool Wrench Set Combination 16 Pc Sae Hi Polish 86014 $311.99 |
|
|
Tekton by MIT 9 pc Combination SAE Wrench Set -Hanging Rack Lifetime Warranty $9.99 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $10.50 |
|
|
NEW Craftsman Fully Polished Combination Ratcheting Wrench Set (8 piece) (SAE) $22.00 |
|
|
MECHANICS SPECIAL—Grip 11 pc Combination Wrench Set SAE $33.56 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $11.69 |
|
|
NEW Craftsman Fully Polished Combination Ratcheting Wrench Set (8 piece) (SAE) $20.99 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $9.99 |
|
|
New MIT 14-Pc. MaxTorq Combination SAE Wrench Set #1937 $57.97 |
|
|
Westward 5MZ27 1/2 inch SAE Ratcheting Combination Wrench $0.99 |
|
|
TRUECRAFT -8Pc- Combo SAE Wrench Set- (8643) $9.98 |
|
|
New Wisdom 14pc. Long Combo. SAE Wrench Set $27.00 |
|
|
KOBALT 7 PC. SHORT COMBINATION WRENCHES SAE $38.00 |
|
|
Craftsman 12 pc Combination Sae Wrench Set NEW Made in USA $12.51 |
|
|
10 Piece Combo Wrench Set SAE 1/4″-3/4″ Mirror Finish $19.95 |
|
|
Danaher Tool 117829 MM 11PC SAE Combination Wrench Set $29.99 |
|
|
32pc Combo CV WRENCH SET SAE / METRIC Stubby / Regular $39.99 |
|
|
NEW 32 Piece Combination Wrench Tool Set Metric SAE Kit Chrome Plated Heavy Duty $89.99 |
|
|
Wel-Bilt SAE and Metric Combination Wrenches-32-pc Set #2111191 $24.99 |
|
|
10Piece 12 Point SAE Stubby Combination Wrench Set 1080 $27.92 |
|
|
NEW Craftsman Fully Polished Combination Ratcheting Wrench Set (8 piece) (SAE) $20.50 |
|
|
NEW Craftsman Combination Ignition Wrench Set (SAE and METRIC)-20 piece set $9.99 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $2.19 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $2.39 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $2.29 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $3.75 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $3.19 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $3.29 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $3.09 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $4.39 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $5.29 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $7.79 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $10.49 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $9.39 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $10.79 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $11.49 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $21.95 |
|
|
Craftsman SAE 12pt Combination Wrench – Any Size – USA Made Wrenches Hand Tools $23.95 |
|
|
Pro Value/ Car Quest SAE Combination Wrenches Many Sizes $4.25 |
|
|
Pro Value/ Car Quest SAE Combination Wrenches Many Sizes $2.75 |
|
|
Pro Value/ Car Quest SAE Combination Wrenches Many Sizes $4.15 |
|
|
Pro Value/ Car Quest SAE Combination Wrenches Many Sizes $7.00 |
|
|
30pc Combo Hex Key Allen Wrench Set SAE/MM Long + Short Arms CR-V $17.20 |
|
|
Craftsman 10pc Ignition Combination SAE Wrenches Set Wrench Tools USA Made $14.95 |
|
|
9 MAC Tools Combination Open Box End & Long Wrenches SAE Metric CLLR MCW S105 $39.99 |
|
|
5PC SAE COMBINATION MAGNETIC HANDLE WRENCH SET & MOUNT $9.00 |
|
|
New Craftsman 25pc SAE/STD Combination Wrench Set 12pt Standard $14.52 |
|
|
Astoria Argenta SAE/2 Big Gulp Espresso Machine $12,187.00 The Astoria SAE 2- Big Gulp Automatic espresso/cappuccino machine features an incredibly high clearance from the cup drip tray to the tip of the brew spouts. The Big Gulp allows the operator to brew the espresso shots directly into a serving cup as big as 24 ounces. The Astoria SAE2- Big Gulp is available in an attractive mirror polished stainless steel and black body style…. |
|
|
Astoria Argenta SAE/2 Boosted Espresso Machine $12,205.00 The dream of all baristas come true! The performance and the power of a three group machine within the dimensions of a two group. The over-sized boiler (15 qts) for high volume of steam, and the heating element (6000 watts) for fast recovery are guaranteed to satisfy all your needs. A micro processor controls operation, providing volumetric measure of water for coffee brewing. The touch pad contro… |
|
|
Astoria Divinia SAE/1 Espresso Machine $6,769.00 Astoria’s divina SAE 1 is a professional one group semi automatic espresso/cappuccino coffee machine with a volumetric programmable brewing time. This model can dispense 4 different coffee dosages and also comes with an independent semi automatic override brew…. |
|
|
Great Neck PSO40 40 Piece 1/4-Inch and 3/8-Inch Drive Socket Set $6.97 No matter what your skill level might be you will eventually find the need to use a socket set to remove or tighten a bolt or nut. Furniture assembly, automotive or appliance repairs, computer parts, cabinet drawers or doors all have nuts or bolts that hold them together. The Great Neck Hardware Machinery 40-pc. socket set contains the most commonly used standard and metric-sized sockets. The 1/4-… |
|
|
Black & Decker RRW100 Ratcheting ReadyWrench $10.99 Ideal for a wide variety of around-the-house tasks, the Black & Decker Ratcheting ReadyWrench is an indispensable tool you’ll reach for time and again. Offering the convenience of color-coded socket sizes for easy visibility, this wrench includes 16 of the most popular standard (SAE) and metric (MM) socket sizes, so you always have what you need to get the job done.Ratcheting ReadyWrenchAt a Glanc… |
|
|
30 Pc Allen Wrench Set- SAE/ MM $3.40 30 pc. Allen Wrench Set SAE/ Metric. Allen wrench set w/ SAE & Metric size allen wrenches. Allen wrench sizes include: SAE -.028″,.035″,.050″, 1/16″, 5/64″, 3/32″, 7/64″, 1/8″, 9/64″, 5/32″, 3/16″, 7/32″, 1/4″, 5/16″, and 3/8″. Metric – 0.7mm, 0.9mm, 1.3mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 7.0mm, 8.0mm, 10.0mm. Great addition to any toolbox includes hard to find sizes… |
|
|
CRESCENT FRR7 7-PIECE REVERSIBLE RATCHETING COMBINATION WRENCH SET (SAE) $109.96 PATENTED RAPID REVERSE SYSTEM FOR FASTER JOB COMPLETIONREVERSES DIRECTION WITH PUSH OF A BUTTON IN THE MOST CONFINED AREASPATENTED RATCHET FEATURE TURNS BOLT WITH JUST 5 HANDLE SWING VS. 30 CLOSED END WORKS IN PLACES DEEP SOCKETS WILL NOT REACH OPEN-END JAW SURFACES ARE PARALLEL TO WITHIN .0015 72 TOOTH RATCHETING MECHANISM RECEIVES SPECIAL HEAT TREAT PROCESSTOOL MEETS ANSI TORQUE LOADS FOR STANDA… |
|
|
CRESCENT FRR7 7-PIECE REVERSIBLE RATCHETING COMBINATION WRENCH SET (SAE) PATENTED RAPID REVERSE SYSTEM FOR FASTER JOB COMPLETIONREVERSES DIRECTION WITH PUSH OF A BUTTON IN THE MOST CONFINED AREASPATENTED RATCHET FEATURE TURNS BOLT WITH JUST 5 HANDLE SWING VS. 30 CLOSED END WORKS IN PLACES DEEP SOCKETS WILL NOT REACH OPEN-END JAW SURFACES ARE PARALLEL TO WITHIN .0015 72 TOOTH RATCHETING MECHANISM RECEIVES SPECIAL HEAT TREAT PROCESSTOOL MEETS ANSI TORQUE LOADS FOR STANDA… |
|
|
Kd Tools EHT9503 9/16 Stubby Combination Ratcheting Gearwrench $13.61 features and benefits: the stubby version of our popular combination wrenches enhanced open end design with surface drive plus technology that prevents fastener rounding size stamped on both sides for ease in identification… |
|
|
Kd Tools EHT9706 $22.87 329-9706 Features: -5 degree ratcheting arc for working in tight areas.-Flex head tilts up to 180 degrees for access to confined areas.-Surface drive provides a stronger grip on fasteners.-No. of Points: 12.-Opening Type: Open/Box.-Length Group: Long.-Material: High Alloy Steel.-Price is for 1 Each. Color/Finish: -Finish: Chrome…. |
