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 After many requests from those of you who have attended our courses, VCERTT has developed a new course, OBD II ELEC- TRONICS I. This is the first half of a two-part course that will cover operation and testing of the electronic components and systems used on OBD II equipped vehicles. This practical electrical course fo- cuses on electrical testing procedures and test- ing common components. You will gain an understanding of why voltage drop testing is so important and practice testing in the lab. Do you know that the only way to effectively test PCM grounds is with a voltage drop test? We’ll test the PCM in the class and demon- strate the appropriate procedure. We’ll also cover tests for solenoids and relays when a new component doesn’t fix the problem. In the second part of this course we will test sensors and outputs with a digital multimeter and by using scan tool data. Learn how to use your scan tool to its fullest potential. NEW COURSE! VCERTT NEWS WINTER, 2005 VOLUME 4, ISSUE 1 CASE STUDY …. EVAP problems are common, we tackle one on a Toyota.…... 3 Automated inspection being tested in Vermont .………….. 2 Chrysler 3.5 L misfire, is it the intake? ……. 4 GM CPFI injectors problems……………. 4 STEVE BELITSOS …… Meet one of our train- ers and hear what he says about teaching .. 4 CHECK OUT THE NEW COURSE OBD II ELECTRONICS I VCERTT: VERMONT CENTER FOR EMISSIONS REPAIR AND TECHNICIAN TRAINING A PARTNERSHIP OF VERMONT TECHNICAL COLLEGE AND THE VT DEPARTMENT OF ENVIRONMENTAL CONSERVATION TO PROVIDE OBDII INFORMATION AND TRAINING TO VERMONT TECHNICIANS Have you ever used your scan tool to establish communication with a vehicle but the information you got didn’t seem to make sense? It could be a case of miscommunica- tion - that is, your scan tool is communicating with the wrong control module in the vehicle. While this is rare, it can be pretty confusing when it does happen. Modern vehicles with automatic transmissions have an engine control module (ECM) and a transmission control module (TCM). With some combinations of scan tools and vehicles, the scan tool will sometimes es- tablish communication with the TCM instead of the ECM. The TCM will only report to the scan tool that the MIL is commanded on and that there’s a DTC if the TCM itself detected an emissions-related transmission malfunc- tion. For other emissions-related malfunctions , the MIL is commanded on and DTCs are set by the ECM. So you could have a situation where for example, the vehicle has a bad oxy- gen sensor, and you can see that the check en- gine light is on with the engine running, but when you plug in your scan tool, it tells you the MIL is commanded off, and there are no DTCs. That’s because the scan tool is talking to the TCM by mistake; if the scan tool were talking to the ECM, it would tell you the MIL is commanded on, and there would be an oxy- gen sensor DTC. Note that the opposite is not true – that is, if there’s an emissions-related transmission malf unction, and the scan tool is correctly talking to the ECM, the ECM will tell the scan tool that the MIL is on, and that there’s a transmission DTC. So the ECM speaks for both control modules, while the TCM only speaks for itself. Also, if the scan tool is communicat- ing with the TCM by mistake, readiness status of monitors will look strange. (Continued Page 4) MISCOMMUNICATION 

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8/6/2019 1-05 crso eletronica

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After many requests from those of you who have attended our courses, VCERTThas developed a new course, OBD II ELEC-TRONICS I. This is the first half of a two-part

course that will cover operation and testing of the electronic components and systems used onOBD II equipped vehicles.

This practical electrical course fo-cuses on electrical testing procedures and test-ing common components. You will gain anunderstanding of why voltage drop testing isso important and practice testing in the lab. Doyou know that the only way to effectively testPCM grounds is with a voltage drop test?We’ll test the PCM in the class and demon-strate the appropriate procedure. We’ll alsocover tests for solenoids and relays when a

new component doesn’t fix the problem. In thesecond part of this course we will test sensorsand outputs with a digital multimeter and byusing scan tool data. Learn how to use yourscan tool to its fullest potential.

NEW COURSE!

VCERTT NEWSV C E R T T : V E R M O N T C E N T E R F O R E M I S S I O N S R E P A I R A N D T E C H N I C I A N T R A I N I N G

A P A R T N E R S H I P O F V E R M O N T T E C H N I C A L C O L L E G E A N D T H E V T D E P A R T M E N T O F E N V I R O N M E N T A L C O N S E R V A T I O N T O P R O V I D E O B D I II N F O R M A T I O N A N D T R A I N I N G T O V E R M O N T T E C H N I C I A N S

WINTER, 2005

VOLUME 4, ISSUE 1

CASE STUDY ….

EVAP problems are

common, we tackleone on a Toyota.…...

3

Automated inspection

being tested in

Vermont .…………..

2

Chrysler 3.5 L misfire,

is it the intake? …….

4

GM CPFI injectors

problems…………….

4

STEVE BELITSOS ……

Meet one of our train-

ers and hear what he

says about teaching ..

4

CHECK OUT THE NEW COURSE

OBD II ELECTRONICS I

V C E R T T : V E R M O N T C E N T E R F O R E M I S S I O N S

R E P A I R A N D T E C H N I C I A N T R A I N I N G

A P A R T N E R S H I P O F V E R M O N T T E C H N I C A L

C O L L E G E A N D T H E V T D E P A R T M E N T O F

E N V I R O N M E N T A L C O N S E R V A T I O N T O

P R O V I D E O B D I I I N F O R M A T I O N A N D

T R A I N I N G T O V E R M O N T T E C H N I C I A N S

Have you ever used your scan tool toestablish communication with a vehicle butthe information you got didn’t seem to makesense? It could be a case of miscommunica-

tion - that is, your scan tool is communicatingwith the wrong control module in the vehicle.While this is rare, it can be pretty confusingwhen it does happen.

Modern vehicles with automatictransmissions have an engine control module(ECM) and a transmission control module(TCM). With some combinations of scan toolsand vehicles, the scan tool will sometimes es-tablish communication with the TCM insteadof the ECM. The TCM will only report to thescan tool that the MIL is commanded on andthat there’s a DTC if the TCM itself detected

an emissions-related transmission malfunc-tion. For other emissions-related malfunctions,the MIL is commanded on and DTCs are setby the ECM. So you could have a situationwhere for example, the vehicle has a bad oxy-gen sensor, and you can see that the check en-gine light is on with the engine running, butwhen you plug in your scan tool, it tells youthe MIL is commanded off, and there are noDTCs. That’s because the scan tool is talkingto the TCM by mistake; if the scan tool weretalking to the ECM, it would tell you the MILis commanded on, and there would be an oxy-gen sensor DTC. Note that the opposite is not

true – that is, if there’s an emissions-relatedtransmission malfunction, and the scan tool iscorrectly talking to the ECM, the ECM willtell the scan tool that the MIL is on, and thatthere’s a transmission DTC. So the ECMspeaks for both control modules, while theTCM only speaks for itself.

Also, if the scan tool is communicat-ing with the TCM by mistake, readiness statusof monitors will look strange.(Continued Page 4)

MISCOMMUNICATION

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VCERTT NEWS VOLUME 4, ISSUE 1Page 2

Does doing away with all the OBD forms, log sheets,

bulletins and other paperwork associated with Vermont’s vehi-cle inspection program sound good to you? Well the State of Vermont is planning changes to the program that would do justthat!

Most people agree that Vermont’s annual emissions and safetyinspections are an important and cost-effective way to help pro-tect the health and safety of Vermonters. But there is also gen-eral agreement that the current method of collecting and man-aging data from the inspection program needs serious improve-ment. The paperwork is a burden for inspection stations and thestate, there’s a high error rate with paper forms, a paper-basedprogram makes it far too easy to cheat, and it’s very hard forthe state to measure the overall effectiveness of the inspectionprogram.

An independent evaluation of Vermont’s vehicle inspectionprogram concluded that the current data collection and man-agement procedures are inadequate, and recommended an elec-tronic data collection and management system as the solution.The benefits of switching to an electronic system include: 1)elimination of paperwork, 2) allowing much more effective andtimely communication between inspection stations and DMV,3) improved accuracy of inspection data, 4) reduction of fraud,5) much more efficient and effective enforcement, 6) allowingmeasurement of the overall effectiveness of the inspection pro-gram, and 7) reduced costs.

To help evaluate how electronic data collection and manage-ment would work in the real world of Vermont inspection sta-tions, the state has been conducting a pilot project for nearly 3years now. A variety of electronic data collection systems havebeen tested in a number of different inspection stations aroundVermont. These systems collect the safety inspection results,automatically collect the OBD inspection results, send the re-sults to a centralized database, and print out a report for thecustomer. The stations participating in this project range from ahigh-volume dealership, to a small two-person repair shop,

NO MORE PAPERWORK?!

ABOUT VCERTT NEWS:The purpose of this newsletter is to provide specialized information to the front line: you, the technicians, service advisors and man-agers in the field handling repairs and customers. The OBD Inspection Program is now well established. While the OBD inspec-tion itself is an easy addition to the VSI we know that repairing OBD II faults may not be as simple. The success of the OBD In-spection Program falls largely on your ability to perform effective repairs. VCERTT is committed to trying to help. We offer this

newsletter to provide information and a forum for discussion. We ask you to call or email us with your questions or suggestions.When you have a troublesome vehicle repair related to OBDII, we’d like to hear about it. If you have problems with a particularvehicle or a scan tool, give us a call. We may be able to help and we can pass along relevant information. We’re always lookingfor test vehicles for our Case Studies - let us take your problem vehicle and attempt a repair, no charge for our time, just help foreveryone.

CALL US AT: 802-238-3211 OR EMAIL US AT: [email protected]

with everything in between. The pilot project has demonstratedthat electronic data collection and management can work well inVermont, and all of the participating inspection stations stronglyprefer the electronic systems over the old paper-based system.When asked if they would like to give up the electronic system

and go back to the paper-based system, one inspection stationreplied “Over my dead body”!

After a thorough evaluation of options for integrating electronicdata collection and management into the vehicle inspection pro-gram on a full-scale basis, the state, with lots of input from in-spection stations, has selected an option that is considered thebest fit for Vermont. This option will involve the state choosing acontractor to supply and maintain test equipment to inspection

stations, and to manage a vehicle inspection database. The con-tractor’s costs will be covered by a per-test fee paid to the con-tractor by inspection stations. Inspection stations will pay no up-front costs for the test equipment. This option will place the leastburden on inspection stations, will have lower costs and requireless management overhead, will avoid compatibility and account-ability issues between equipment providers and the databasemanager, and will result in a simpler training program. Many of the details still remain to be worked out, but the overall goal is toswitch to electronic data collection and management for the vehi-cle inspection program within the next two years.

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This summer we completed work on a 1998 ToyotaCamry with an evaporative emissions system (EVAP) fault.The Toyota came to us with the MIL on and DTCs P0440(Evap system malfunction), P0441 (Evap system incorrectpurge flow) and P0446 (Evap vent control solenoid circuit)stored. In our research on the system, which included a visit tothe Toyota Technical Information System website (http:// techinfo.toyota.com), we found a technical service bulletin(TSB) that was published for Toyotas with DTCs P0440,P0441 and P0446. The TSB applied to all Toyotas from 1996-2001 with the "early" type EVAP system. All passenger carsand light trucks through 1999 used the early type system. InMY 2000 the passenger cars switched to the late type system.

The TSB recommended replacing the EVAP system assemblythat included the canister, the valve assemblies, the vapor pres-sure sensor and the vapor pressure sensor vacuum switchingvalve. We decided to test the system and components to deter-mine if we could isolate the problem and provide a more costeffective repair.

This Toyota EVAP system is a bit unusual. It uses atraditional purge solenoid controlled by the PCM althoughToyota calls this an EVAP vacuum switching valve (VSV).The system uses a mechanical, spring-loaded air valve to keepthe system sealed unless the purge valve is operating. Whenvacuum reaches the air valve during purging, it unseats the airvalve to allow fresh airflow into the canister. During refueling,

a drain valve within the same assembly unseats to exhaust ex-cess pressure from the canister. The system does not have avent solenoid. A vapor pressure sensor is installed in a line be-

VCERTT NEWS VOLUME 4, ISSUE 1

tween the fuel tank and the canister. During monitoring of thesystem, the vapor pressure sensor VSV allows the vapor pres-sure sensor to monitor either fuel tank pressure or canister andline pressure. The vapor pressure sensor VSV is just a typicalsolenoid that switches the passage to the vapor pressure sensorfrom the fuel tank sensing line to the canister sensing line.

After extracting the DTCs we used our smoke leak detector to check the system for leaks. We found a small leak atthe canister where a small hose to the vapor pressure sensorVSV had become disconnected. After reconnecting the line wecould detect no leakage in the system.

Next we wanted to check the EVAP VSV and the va-por pressure sensor VSV. We removed the solenoids from thevehicle for better access. Toyota specifies that the VSVs should

have resistance across the solenoid coil of 30-34Ω at 68°F

(20°C). Both of the solenoids had appropriate resistance. We

were also instructed to check for continuity between the termi-nals and the VSV case. We did not have continuity, the wind-ing was not shorted to ground on either VSV. The next test is

VCERTT CASE STUDY: TOYOTA

EVAPORATIVE EMISSIONS SYSTEM FAULTS

The vapor pressure VSV is bolted onto a bracket on the

canister. The air valve sits below it with the larger hoses.

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to activate the VSV and test its mechanical operation. We triedto blow from one port through the valve to the other with no

power applied to the solenoid. The normally closed solenoidfunctioned properly in this portion of the test; it did block flow.Next we used a battery and jumper wires to provide power andground to the solenoids. Neither one clicked, nor did they allowairflow through the solenoid. They failed to open as theyshould with power applied to them.

When we got the new VSVs we tested them before weinstalled them and they did function as we expected theyshould. With the new parts on the vehicle we rechecked thesystem for leaks and found none. We cleared the DTCs. Toverify our repair we used the drive cycle routine for the evapo-rative system monitor which we also found on the Toyota web-site. It involved a fifteen minute drive after a cold start. After

the drive we found the EVAP monitor status ready, meaningthat the PCM had performed the system testing. We checkedfor pending or active DTCs and found none. Had the PCM de-tected a problem with the system it would have at least set apending code on the first trip so we considered our repair a suc-cess. The customer spent $86 on parts and happily reports thatthe MIL is still off.

VCERTT:

VERMONT CENTER

FOR EMISSIONS REPAIR

AND TECHNICIAN TRAINING

VCERTTATTN: BETSY DORRIES

VERMONT TECH1 MAIN STREETRANDOLPH CENTERVT 05061

PHONE: 802-238-3211FAX: 802-728-1010

EMAIL: [email protected]: www.vcertt.org

Steve Belitsos has been involved in the auto repair industry since 1974. He hasbeen an ASE Master Certified Technician since 1977 and has held the L-1 Advanced En-gine Performance certification since it was firstoffered. In 1994, he began teaching at Porterand Chester Institute in Chicopee, MA andcame to VTC in 2000. He says, “ I very muchenjoy teaching the VCERTT modules becauseit gives me the opportunity to share skills with

fellow professional technicians. I can explainthe operating principles of a particular compo-nent or system and at the same time, get feed-back from the class participants on repair situa-tions that they see in practice. The mix is verydynamic, enlightening and fun. Being a pizza-ofile, I also appreciate the opportunity to sam-ple various pies in Brattleboro and Rutlandwhile socializing with fellow techs before the classes.” Call 238-3211 today to register!

MEET VCERTT’S STEVE BELITSOS

GM CPFI PROBLEMS

By now many of you have probably experienced problemswith GM’s central port fuel injection used on many trucks since themid 1990s. One of the more difficult problems to detect is an inter-mittent misfire, usually after a short period of hot soak. The cus-tomer drives the vehicle, goes into the store, comes out fifteen min-utes later and the engine is misfiring seriously. It will turn the MILon but may also cause a misfire significant enough to cause a flash-ing MIL. By the time they bring the vehicle to you it is runningfine. You may or may not be able to duplicate the concern. Theproblem is that injectors are sticking closed after they get heated upand shut off. Some technicians are opting to replace the entire stringof “spider” valves, the injector poppets. Another group of techni-cians swears by GM Techron fuel additive and reports that a dose atevery major service eliminates the problem.

CHRYSLER 3.5 MISSHave you experienced misfire DTCs on Chryler’s 3.5 liter enginethat won’t quit even after all new ignition components? You cancheck the valve timing twice and even replace the injectors. Theseengines may throw a P0300 DTC for random misfire or they may

set single or multiple cylinder spe-cific misfire DTCs. The misfire maybe apparent in the service bay but

less noticeable on the road. A com-mon cause is an intake manifoldgasket leak. The leak is hard to de-tect because it is usually buried un-derneath the intake. Try this tech-nique: use your propane tank with avery small hose and tuck it into thesmall opening at the very front andbottom under the intake. If the RPMchanges when you apply propaneyou have identified the cause.

MISCOMMUNICATION (CONT.)

What you’ll typically see on your scan tool is that the compre-hensive components monitor is ready, but all other monitorsare not supported (or N/A). That’s always a good indicator that

your scan tool is talking to the TCM instead of the ECM.Again, this only happens rarely, but what can you do

about it? Some scan tools identify which control modulethey’re communicating with, and allow you to switch to theother control module. If your scan tool doesn’t have that capa-bility, but what you see on the scan tool doesn’t make sense asdescribed above, you can disconnect the scan tool and try es-tablishing communication again. Sometimes it may take sev-eral tries until you get the right control module. When whatyou see on the scan tool makes sense, then you know you havethe right control module, that is, the ECM.

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