Servicing Cabin Air Filters - Cabin air filters are designed to improve cabin air qual-ity. Failing to service these filters can result in the development of mold, reduced HVAC performance, and in the worst case scenario, ac compressor damage. Restricted air flow to the evaporator core can result in liquid refrigerant exiting the core and enter-ing the compressor, resulting in damage. Always follow recommended service intervals and replace cabin filters if they are “dirty”. - Ray Grooms Dynamic Testing - As we all know, vehicle faults tend to show up when the faulty circuit is being operated, not when it’s idle. For this reason it is important to perform “dynamic” testing of various sensors, circuits, and actuators. Dynamic testing refers to tests performed on circuits under load. Static tests are exactly the opposite, theses in-clude voltage potential and resistance checks. The main difference is being able to see the activity of a functioning component, this is mostly done through the use of amper-age measurements. It’s also a good rule of thumb to allow the component being tested to operate for a minimum of 5 minutes and to put some “stress” on the circuit. Snap throttle testing and load simulators are good ways to accomplish this. - Eric Irwin Sticking Valves in Cold Weather - Winter months commonly result in cold weather faults. In most cases air valves will tend to stick because valve clearances and seals harden and contract. When you suspect this is the case and the packer is inoperative, a simple test procedure can help in determining if the valve is in fact “sticking”. Make sure the packer is in it’s rest position, from here actuate the packer to it’s travel limits. Upon changing directions the air valve should return to it’s at rest position. If continual air leaks are heard, the air valve is sticking. Disassemble the valve for inspection and replace as necessary or service and reinstall. - Sal Guerrero

Scope It!: Current Ramping (Amp Ramp)

What is current ramping? Current ramping refers to the use of an inductive amp clamp probe with a DSO (digital storage oscillo-scope). This test strategy is by far one of the most useful and powerful diagnostic techniques available to technicians. Because the amp probe measures magnetic force and outputs a proportional voltage level to indicate amperage, a DSO is required. Setting up a DSO to measure amperage is relatively easy. Scope Settings; Your scope settings will depend upon how much current you anticipate on the cir-

cuit under test and how much time you need to capture the electrical activity. There are 2 available amp probes 1. 60a probe; This amp clamp has a 20a mode and a 60a mode. 2. 600a probe; This amp clamp has 1 measurement scale; 600a. The scope’s timebase setting can be set intentionally high at 1s per division and then scaled down from there to get the desired display. In the probe selection drop down menu, select either the 60a or 600a probes. The 600a probe will primarily be used for starting and charging system testing. The 60a probe will be used for most of your other testing needs. Conventional fuel injectors will typically have an approx. current draw of .75a while fuel pumps will normally require 5a - 10a, and ignition coils can run at maximum

values of 17-21a. Measurement Procedure; Once you’ve selected the appropriate probe, the amp clamp will need to be zeroed. The 60a clamp is auto zeroing while the 600a clamp is set manually with a thumbwheel dial. Install the current clamp around the desired test point, typically before or after a load around the power or ground supply wiring, and operate the circuit. Key Indicators of Potential Fail-ures; Waveform consistency and uniformity are the primary indicators of failing electrical components. Shorted components will show up as sharp or irregular rises at the beginning of the components activity. Peak to peak analysis and average current draw measurements are also very useful in assessing overall condition. Fig. 1 shows a bad starter and Fig. 2 shows a primary coil signal dropout.

Tech Tips!

Sponsored by your SIC

Newsletter Editors Eric Irwin

Ray Grooms Sal Guerrero

Y Drive Tech Tips Folder Updates!

Reprogramming Bulletin posted! Get up to date info on open reprogramming issues! Soldering guide added to the electronics folder!

Napa AutoTech folder added, view some of the materials available to you through Napa.

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- Eric Irwin

Red trace = cranking current, bad starter shown here, over 500a pre-sent for prolonged period of time.

Fig. 1

Fig. 2

Primary ignition current shown in red, primary voltage in blue. Both traces show good waveforms, the problem

was due to a bad connector and a signal dropout.

Dirty Cabin Air Filters

Amp Clamp & Scope

Air Valve

Diagnosing control modules tends to be an aggravating experience for most technicians and the fact of the matter is that over 50% of the returned cores have nothing wrong with them. Fortunately, con-trol module operation can be broken down into 5 basic components and understanding this basic operation can help us correctly diag-nose faulty modules, from Powertrain to Parking Assist modules. It’s important to realize that the bulk of failed modules is the result of overloaded tranisitors (drivers) internal to the module. The drivers become overloaded due to high current draw, most often

associated with failing actuators. A module is simply a “brain”, it receives sensor inputs and com-mands an output based on internal programming and external sensor values. The most basic checks when testing any module are checking power and ground sources, load testing these module sup-plies is the best way to prove them out. A module consists of 5 basic components, they are: 1. Volt-age Regulator. Modules require very stable voltage levels to operate, thus “reference voltage”. Al-ways check reference, ignition and B+ voltage values when diagnosing modules. 2. An Amplifier. Electrical inputs to the module need to be “clean” and free of interference, the amplifier increases signal strength and filters out excessive electrical noise. From here, the signal is passed through to a 3. Analog to Digital Converter (ADC). Computers are digitally operated, meaning the signal must be “on” or “off” (i.e.; 1 or 0). The ADC takes care of this signal conversion. These 3 components: the voltage regulator, amplifier, and ADC (and sensors) are responsible for delivering clean and accurate signals to the microprocessor. 4.The microprocessor is the “brain” of the operation, there are 3 separate memory modes within the processor, these are read only memory, random access memory, and keep alive memory (ROM, RAM, KAM). Read only memory is permanent and pre-programmed memory that provides lookup tables, input responses, and maps. RAM is the scratch pad and calculator of the module, it performs necessary calculations to determine desired outputs, this memory is cleared every time the vehicle is turned off. KAM is similar to RAM except that it receives constant B+ and retains its information. KAM is responsible for storing all adaptive values (shift timing values, fuel trims, etc...) The last component of a module is the 5. Driver (s). The driver is responsible for providing a means to control output actuators, transistors are commonly used as drivers.. Visit Napa AutoTech at www.napaautotech.com for an introduc-tory training course into PCM Operation and Testing.

Our shop has recently purchased the DrewTech CarDaq-M J2534 Pass Through Reprogrammer. With this specialty piece of equipment we can now perform calibration updates to a vehicles on board modules. J2534 is a SAE standard which mandates that all light duty vehicles sold in the US allow for emission related modules to be recalibrated by aftermarket tooling. The CarDaq-M is a modular system which allows for expansion modules to be added as technology changes. The device supports the J2534 and J2534-1 protocols which supports engine and transmission modules on all makes and models, and adds additional functionality for Ford, GM and other manufacturers. Fixes pro-vided by reflashes range from shift timing to exhaust smells in the cab!

Cover Story: Basic PCM Operation & Testing

Tools & Equipment; DrewTech CarDaq-M J2534 Pass Through Device

Volume 2 Issue 1

Tech Tips! “By The Techs, For The Techs”

Happy New Year! Napa AutoTech

training is still available! Get access to ASE Test Prep and training modules!

Visit the Y Drive Tech Tips folder today for various auto related info!

Tech Tips is currently seeking individuals wishing to contribute to the newsletter, see Sal, Ray or Eric.

Jan. 2012

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Eric Irwin

Eric Irwin

In This Issue Cover Story 1 PCM Basics Tools & Equip. 1 CarDaq-M Case Study 2 98 Crown Vic The Electronics 2 Corner Soldering Guide Industry News 3 Smog News Auto 101 3 Parasitic Drain

Testing Tech Tips 4 Cabin Air Filters Dynamic Testing Air Valves in Cold Weather Scope It! 4 Current Ramping

Case Study: 98 Ford Crown Victoria Crank & No Start Vehicle; 98 Ford Crown Victoria Interceptor, 4.6L Symptom; Vehicle came in on the hook with a complaint of a crank and no start. Preliminary Inspection and testing; The first step performed was a visual inspection, no obvious problems were found. Next I in-stalled a fuel pressure gauge and a scan tool. KOEO fuel pressure appeared good at 38psi, the spec is 35-45 KOEO and 30-45 KOER. Residual pressure held at approx. 36psi. KOER pressure was 40psi, and a snap throttle resulted in a peak of near 45psi. Scan Test Re-sults; No DTC’s stored or pending, all monitors ran and passed, mode 6 results pass. At this point I suspected an intermittent failing fuel pump with a bad commentator segment, now I just needed to gather enough evidence to support my theory. My first step was to elimi-

nate the air induction system as a culprit. Scan tool PIDS revealed the MAF gm/s at idle to be around 4.3gm/s. Using the 1gm per liter analogy this value is considered normal. MAF voltage reads approx. .8v, around .5 - 1v is expected at idle. A snap throttle shows a peak of close to 4.3v - all of which is good. Reviewing fuel trims at idle, 2500rpm and during loaded conditions confirmed what the MAF readings were telling me, the air induction system is functioning normally. So the air induction system seems to not be a suspect, and we already have fuel trim inspection results which show total fuel trims to be w/n acceptable levels under all driving conditions. A test drive was performed while using the scanner to graph the pre o2 sensors and fuel trims. During a WOT application we can see that OL occurs (power enrichment mode) and the o2’s respond rich, which indicates fuel volume is okay. At this point I’ve confirmed that the

problem is not a hard fault (always present) and in order to assess the condition of the fuel pump I need to perform some dynamic test-ing, which simply means testing a component under load. Using the Picoscope, I performed an amp ramp assessment of the pumps inter-nal condition. This simply means installing the 60a amp clamp in 20a mode at the pump power supply (note - it is important to clamp the probe as close to the load as possible, not doing so can result in inaccurate waveform representation as amperage activity may be smoothed out or affected by other circuits being powered by the same source). Fig. 1 shows the results, here we can see the pump is an 8 segment pump. There are 3 suspect irregularities in the waveform; all of which indicates potential bad contact areas at the brushes and segments. The other important thing to note is the avg. current draw which is 5.75a in this capture.. This waveform provides the proof we need to replace the pump. Repair; A new pump was installed and another amp ramp measurement was taken. Fig. 2 shows the new fuel pump with an avg. current draw of 4.3a and a relatively uniform peak to peak wave-form. In conclusion we can see that even though the no start symp-tom could not be duplicated we were still able to condemn the most likely suspect by using diagnostic equipment to assess the condition of suspect components. Just for kicks I cut open the pump and removed the motor, visual inspection of the commentator segments and brushes revealed what the scope showed us, multiple poor contact areas.

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- Eric Irwin

The Electronics Corner: Soldering Guide Soldering is a critical skill that all technicians should use. With a little “know-how” and some practice, we can all become experts at soldering in no time! What will you need? You will need a soldering iron, solder, and something to solder! What is Solder? Solder is an alloy mixture of tin and lead, most commonly available in a 60% tin to 40% lead ratio. Rosin core solder is very common and already con-tains the flux in the solder. What is Flux? Flux is simply a chemical cleaning agent, it is corrosive and cleans the metal as it is being soldered. Soldering Steps - 1. Turn on your soldering iron and allow it to warm up for a couple of minutes. 2. Wipe the tip with a damp cloth to clean it, then melt a little

solder onto the tip. This is called “tinning” and will help the heat flow from the iron tip to the joint (Tinning only needs to be done occa-sionally). 3. Touch the soldering iron tip against the component lead and surface where the solder joint is to be made. Depending on what type of component you’re soldering, you may need to use a heat sink to help dissipate excessive heat. 4. Apply the solder to the joint. It is critical to let the solder melt against the joint and not the iron tip, this allows the flux to clean the surfaces being soldered and ensures a good solder joint. Allow the joint to cool before handling. To see this soldering guide visit the Electronics folder in the Y drive!

8 Segment pump shown between cursors

These 3 points indicate our suspect areas

Avg. current draw at 5.75a

Fig. 1

Fig. 2

Notice how much more “uniform” the waveform is? Also the avg. current draw has been reduced to 4.3a w/ this new pump, and the peak to peak measurement is less.

- Sal Guererro

As you may have heard, changes to the current smog program are on their way! In a nutshell, the proposed changes for 2012 and 2013 are targeted at restructuring the smog program in order to reduce cost to motorists and to “weed out” smog shops / technicians that do not follow state guidelines. The 2012 proposed changes will separate the current Test & Repair license into 2 licenses; an Inspector only license and a Repair only license. Technicians will be required to obtain both licenses to be qualified by the state as Test & Repair technicians. The Intern Technician License will be

eliminated along with the EA and EB (Enhanced and Basic Areas) designations. Smog shops will also fall into these 3 categories; Test only, Repair only, or Test and Repair. These restructuring changes are scheduled to take place August 1st of 2012. As for testing vehicles? These proposed changes are set begin in mid-2013. Vehicles 2000 and newer will only be required to have an OBD2 test performed to check for DTC’s in relation to continuous and non-continuous monitors. It is estimated that this could reduce the costs to motorists by $180 million annually! As for 1999 model year and older vehicles, they will be required to have tailpipe testing done. The kicker here is that only smog shops with the highest BAR ratings will be allowed to test these vehicles. While this news is still “unofficial”, it makes sense considering the results of an independent review of the Smog Check program conducted in 2009. The results indicated that 19% of ve-hicles which had passed at smog stations failed testing by the BAR, and 49% of vehicles that had failed BAR testing passed at smog stations. For more information visit the Y Drive and see the Smog folder located at Tech Tips>Articles>Smog. You can also visit www.smogcheck.ca.gov for even more information. -Ray Grooms

Auto 101: A New Approach to Testing Parasitic Draw Today’s vehicles consist of more electronics than ever before. A vehicle can have as few as 5 control modules to as many as 100 or more! With all of the modules talking to each other over a communications bus, a problem in one area could be the result of an unlikely sus-pect. What this means is; we must find a new solution to an old problem. In the past, testing for parasitic drain meant installing an ammeter in series with the battery’s negative cable to measure amperage, a good rule of thumb was 50ma or less. If an excessive value is present then you’d proceed to remove fuses until the value changed indicat-ing the problematic circuit. Nowadays, parasitic drain can be as low as 15ma and disconnecting the battery will result in the powering down of multiple modules possibly causing the fault to disappear. Pulling fuses can also cause the para-sitic drain you’re attempting to locate to disappear. The new test procedures to locate parasitic drains include using a voltmeter to measure voltage drop in mv across fuses, or an amp clamp to measure current flow in ma across a fuse. Fused extension leads are available to assist in this test through the use of a scope, meter, or stand alone amp clamp. The size of the fuse and its rating will deter-mine the expected voltage drop / amperage flow that you will expect to see. Larger ratings will result in more current flow which adversely results in higher temperatures, thus high voltage drops. Standards for this testing procedure have not been developed or made available as of yet. What this means is; using this test procedure will require a technician to develop their own testing methods and values. A general rule of thumb that can assist the technician is to measure voltage drop / current flow across fuses of the same type and rating. We would expect to see similar values on circuits that are functioning normally while they are at “idle”. A circuit with parasitic drain would result in a higher than “normal” voltage drop / current flow. Ideally, a technician would test drive the vehicle and operate all of its systems then allow the vehicle to go to “sleep”. Once this has happened, you would proceed with the parasitic drain testing methods listed above. Make sure that you don’t open a door or do anything that will “wake up” the network.

Industry News: Proposed Smog Program Changes (2012 / 2013)

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- Ray Grooms