TECHTIPS April 2015 (TIPS 0415)

TECHTIPS APRIL 2015

TECHNICAL SERVICE BULLETIN

02 FA AND FB ENGINE CRANK SPROCKET TIMING MARK - IMPORTANT REMINDER

As a reminder, to avoid unnecessary DTCs setting after engine reassembly, when aligning timing components on the FA and FB engines, the crankshaft timing chain sprocket MUST  be installed with the OVAL-SHAPED (oblong) timing mark facing front  as shown below.

Be advised, there is also a half-moon shaped mark found on the back-side of the crank sprocket. This mark can be easily mistaken for a timing mark like in the example photo below which clearly shows the crank sprocket installed backwards. Use this mark to help identify the back-side of the crank sprocket ONLY  .

07 IDENTIFYING ELECTRICAL HARNESS CONNECTORS

Scenario:  When diagnosing a DTC and familiarizing yourself with the trouble tree, the connector number and terminal layout is provided but, on the actual vehicle, you discover there are multiple connectors which have the same terminal configurations and wire colors. Although this does not occur often, you still need to be able to determine which connector the Service Manual is referencing for proper diagnosis.

Example:  DTC P0716 on a 2013 Outback with CVT transmission. The photos below show 2 very similar connectors (AT4 and AT5), both with the same wire colors and located very close to each other on the transmission. The difference is, one connector is dark gray in color while the other is light gray. In this case, doing the pin tests on the wrong connector resulted in both an incorrect repair diagnosis and unnecessary part replacement.

Remedy:  Refer to the end of the Wiring System section of the Service Manual where you will find the handy harness connector chart shown below.

The diagnosis chart for the DTC references connector AT5 (light gray as shown in the chart).

This chart can also be found by entering the specific harness connector number directly into the search box:

The Electrical Component Location (term is also searchable) chart also comes in handy with identifying the location of the specific component you are diagnosing. (This illustration ties in with the DTC P0716 referenced in this article's example).

07 ELECTRICAL DIAGNOSIS AND AFTERMARKET EQUIPMENT

As we all know, our vehicles are becoming more and more electronically-controlled with the number of control modules continuing to increase all the time. These modules work on specific voltages and current, typically low-voltage and low-current to help protect the circuits inside them. Before diagnosis of an electronic concern is begun, it is imperative to perform a thorough inspection of the vehicle for any aftermarket electronic devices. Ideally, the Service Advisor would question the customer to gather pertinent information to help with your diagnosis like: When did this condition start happening? Did you have any aftermarket equipment installed before the concern happened?...etc. Most of the time, an erratic electronic failure of a single item can be attributed to a loose ground or poor connection but, a complete failure of a single or multiple items often ends up being attributed to a power failure. What contributes to erroneous voltages? One cause can be attributed to the ever-growing popularity of LED lighting. LEDs are low-power devices which also draw relatively low current and are designed to work on specific, current-controlled circuits. To install LED lighting on a vehicle not originally designed to utilize it, LED bulbs with internal load resistors can be used or, bulbs not having internal load resistors can also be used as long as external, in-line load resistors are installed in parallel with them.

Because LEDs operate with low-resistance, if they are installed without the proper load resistor in a circuit designed for a high-resistance (incandescent) bulb, the device could cause the related circuit to be mistaken by the applicable control unit as "open". An example of this would be a turn signal or hazard flasher blinking rapidly similar to when a bulb is burned out or maybe a dash warning light coming on to indicate a bulb is out. Another more costly condition would be a large amount of current (surge or voltage spike) from a non-resistor LED making its way back into a control module and damaging a circuit (vehicles with CAN circuitry are the most susceptible to this type of failure).

12 FUEL DOOR FREEZE-UP

Either a CAREFUL "tap" with the side of your closed hand to break the ice or application of a spray de-icer product directly onto the indicated area of fuel door has provided good results in restoring normal operation. Spray de-icer products like those shown in the example photos below are readily available at major retail outlets and are all specifically described as being safe for application directly onto the vehicle finish.