Giammalvo Files
Mark Giammalvo

Mark Giammalvo specializes in driveability diagnostics at his family business, Sam Giammalvo's Auto Sales & Service, Inc. in New Bedford, MA.   

Mark, who has been with the business for over 20 years, is an ASE  Master Technician and Parts Specialist. He also holds the ASE L1 certification, and has an associates degree in business management.
Mark is also a writer for Motor Age Magazine and is the past secretary of the Alliance of Automotive Service Professionals, (AASP).

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Cruising With Information Lockout

(Printed in the Journal of The Alliance of Automotive Service Providers, AASP) 

In the past 10 years or so, there is little doubt that vehicles have become much more difficult to diagnose and repair. I'm not talking about the mundane exhaust or brake repairs but the elusive electronic problems that crop up on our modern day vehicles.

This complex issue of diagnostics and information lockout recently hit home for me, as it involved one of my own vehicles, a 1997 Nissan Maxima.

For the past several months, the cruise control has been inoperative. At first, the cruise would work intermittently, but as of late, it had finally died. The power light works when you turn on the master switch but when you get up to highway speed and push the ‘set' button, the cruise light in the cluster just blinks on and off at a steady rate.

A check of Nissan Service Bulletins did not reveal any similar conditions. Since I owned a copy of the actual 1997 Nissan Maxima Service Manual, I thought I would browse through that next. This is where things got interesting. The service manual listed a trouble tree, (TT), having you check to see if the cruise light blinks when you attempt to push the set switch. Then the TT advised testing the vehicle speed sensor, (VSS). I presumed the VSS was fine since my speedometer and transmission both exhibited normal operation. The next step in the TT was to check the ASCD pump wiring and internal resistance. The TT stated that the Ohms reading should be checked at the pump's connector on three of the four wires. The TT listed an appropriate Ohms range for each wire. Finally I had something solid!  Two of the three wires tested out of range. I ordered the 325.00 pump, waited and prayed.

The pump arrived at the end of that same week. I swapped out the pump and hit the highway. Bang, same problem: cruise inoperative and a blinking cruise light. A quick test of the new pump revealed a disturbing revelation. The internal Ohms reading on the new pump was the same as my old one. As we have all seen, time and time again, the service manual had an error and this one just cost me 325 smackers.

Now we get into the information lockout/complexity issue. The service manual suggested that many tests could be performed with the Nissan Consult Scan Tool. Some available tests were: steering wheel cruise switch status, cruise VSS status, ASCD pump command, and more. As with most independent service shops, we don't have the Nissan Consult Tool. I am not even sure we would even be allowed to purchase it from Nissan. (Regardless, we could never afford all the dealer scan tools anyway, not to mention the annual update costs for each tool).

Well, I connected our Snap-On Scan Tool, but, no dice. As usual, the aftermarket scan tools cannot perform the same tests as the dealer Nissan Consult Tool. Sometimes this issue of information lockout is more an issue of a "lack of reasonable tooling costs" to be competitive. Let's face it, you cannot be as competitive as the dealer of they have specialized tools that make the repair more efficient and less costly to the consumer. The shop with the specialized tools is going to repair the car at less of a dollar hour labor cost than the shop that has to spend more time testing those same items manually, without the special tools.

Regardless, it was time to send my baby to the dealer. I called the Nissan dealer that we contract service work with any they gave me an appointment. I took the Nissan in on the assigned day with a written list of what I had done so far. After some checking, the dealership technician recommend trying a new cruise control computer, (ASCD module), to the tune of 425.00. I gave them the go-ahead and they ordered the part. The following week when I returned, the technician installed the module but reported that the problem was the same. Fortunately the dealership agreed to swap my computer back and not charge me for the new one.

After about 5.5 hours of labor, (460.00 dollar's worth), the cruise was fixed. The technician eventually discovered that a cruise control switch on the brake pedal had gone out of adjustment. A few turns of a wrench and I was back in business. Not a cheap repair but I was just happy that the cruise was now finally working again.

As a final note, not to add insult to injury, I remembered reading a post about this switch causing problems on the IATN e-mail forum. Problem is, it was one of those items that the service manual stated could "easily" be tested with the "Consult Tool."

Could I have spent an hour or so reading the wiring diagram and trying to figure out the function of some of these electronic parts? Sure, but at what cost when the same results can be had by others with better and faster methods?

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