My last two installments of Tech to Tech focused on the need to have a critical eye when servicing a client's vehicle in the service bay. This is a prime opportunity to identify situations with your customer's car that otherwise may go unnoticed. If we're keeping a critical ear when we drive our customer's car, and having a critical eye when we pop a hood open, let's take the next logical step and find additional information when we are accessing our shop's information database.

When addressing situations requiring a diagnosis and analyzing a customer concern, I often consult General Motors Corp.'s tried-and-true, strategy-based diagnostics guide. The chart begins with:

• Verify customer concern
• Perform visual inspection
• Conduct diagnostic system checks
• Check for any applicable technical service bulletins (TSBs)

Certainly it makes sense to always verify the customer complaint and perform visual inspections, but when we get to the box that states "Check for any applicable TSBs," how often do we do it? I have to admit I sometimes get a little lazy and just perform a quick search. If I don't get a quick hit, I grab the scanner, check another car, talk to someone standing at my office door, etc. However, I have found on more than one occasion that spending some good quality face time with your PC can pay off big time when chasing down those quirky clunks or addressing an intermittent, fill-in-the-blank issue.

Some TSBs have become so popular that they are a part of our diagnostic routine. For example, if a malfunction indicator light (MIL) is on, what is the first thing you ask your customer? "Did you just fill the tank with gas?" The cause could be a loose gas cap.

The Shifty Ranger

Gasket has fractured and migrated away from the valve body.

A customer came to me recently with a complaint of, "The car shifts pretty hard sometimes or takes a long time to shift." I was able to verify the complaint with a fairly short test drive. Since the vehicle had low miles, and all of the basics seemed to be in order, I went to my PC.

I have an online version of a big-name information provider at my fingertips. So I searched for the concern under the "symptoms" heading in one of my databases, but got no hits. I then consulted the International Automotive Technicians' Network (iATN) and searched the "closed with fix" heading under the "search fix database" heading. It was here that I found a reference to low-line pressure, and a factory TSB number.

I then took my new information to a friend who had another big-name information provider on his computer. I performed the same search and bingo ... I found a TSB that addressed my concern almost perfectly. It addressed a revised transmission valve body service kit and updated valve body separator plate. As I read, I got the impression that if I were to call my local Ford parts department with this kit number, he would respond with "How many do you want?" I must admit that I felt a sense of relief when I heard that the kit contained a revised separator plate with gaskets "glued" to the plate. This fact hinted at what I might find when I pulled the pan.

Being a pull-the-pan-off-only-on-occasion kinda guy, I didn't realize right away what I was looking at, but after some scrutiny, I saw it. There was a chunk of split gasket reaching out from between the valve body and the case (see picture).

In this situation, the search for the TSB saved my customer the agony of a transmission replacement.

Driveability Diagnosis

We have all had the car with the intermittent concern that drove us nuts; how often do you consult the TSB list for help? While searching the same model above, I found the following headings, which could certainly help cure certain headaches:

• Hard start, engine hesitation, rough idle. These symptoms may be caused by the chafing of a wiring harness under the driver's seat.
• Lean driveability symptoms; mass air flow (MAF) contamination. This is a classic contamination issue, and is not exclusive to this application. MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor overestimates air flow at idle (causes the fuel system to go rich) and underestimates air flow at high air flows (causes fuel system to go lean). This means long-term fuel trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.

A recent Identifix bulletin in a past issue of AutoInc. identified a dirty MAF as the cause of low transmission line pressure, a slipping transmission, and two replacement transmissions!

Check Safety

Gasket pushed out from around servo cover.

While you're in there searching for the "magic bullet" that will solve your head scratcher, pay attention to any that involve safety. For example, I often run across some that address recalls for faulty seat belts or defective turn signal switches. Either way, this is a great way to enhance your customer's visit to your shop. Other important bulletins I've come across recently include:

• Many manufacturers are recommending that front disc brake rotors be machined only on the vehicle, and they often list a specific manufacturer of on-car lathe.
• Another bulletin called "Frame Cracking" supplies numbers for reinforcement plates if your customer complains of a popping noise from the floorboard, and you find visible cracks on the inside of the frame.
• "Front Brake Caliper Mounting to Steering Knuckle Thread Repair" talks about the "approved" way to repair threads and save the knuckle from needing to be replaced. You and I may have already done the thread repair without the bulletin, but it does make it an easier sell when you can show a printed manufacturer procedure.

Expand Search to iATN

I have used iATN to help repair more vehicles than I can count. On occasion, the TSB is actually a response from a technician who has experience with a particular make or model that I am seeing for the first time. Other times I often find a clue imbedded in the "closed with fix" section.

One recent thread discussed a 2002 Honda that cranked but would not start. The car had no spark, and all normal tests did not point to any of the ignition components as the culprit. Another tech suggested referring to the immobilizer light (green with picture of a key) on the dash. If you turn the key on, the light should come on for two seconds and then go out. If the light turns on for two seconds then flashes, your problem is with the immobilizer system.

It turns out that the vehicle had been stolen recently, and the new keys were not registered with the car.

Taking full advantage of all your resources can make your life easier and more productive, and should be one of the first steps to take in your diagnostic routine after performing all of the "normal" methods of diagnosis. Sometimes TSBs actually tell you what the failure parameters are, and can help you duplicate the customer concern. That being said, it pays to reference these early in your diagnosis.

ASA's Mechanical Diagnostic Solutions