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Is It in Drive or Not?Posted 11/5/1997By Mitch Belew
It doesn't matter how long a technician has fixed cars for a living, we all are guilty of forgetting the basics from time to time. Nothing can make you feel more like a fool than spending a lot of time diagnosing a problem that you might have found right away if only you had checked the basics. In some cases, it is easy to assume something else is the cause. For example, an inoperative speed control on a 1988 Lincoln Town Car threw me a curve simply because I didn't check the basics first -- at least, not all of them. The speed control on a 1988 Lincoln Town Car is an integrated system, meaning the powertrain control module is the amplifier. The first thing you should do if it is inoperative is to pull codes -- to check for throttle position sensor and vehicle speed sensor codes. I did exactly that. There were no trouble codes. Then I proceeded to check the speed control switch voltages, servo operation and vehicle speed sensor output. All were good, but the speed control was still inoperative. After scratching my head for what seemed like a few hours, it finally dawned on me to see if the powertrain control module "knew" that it was in drive when the shift indicator was in "D." Had the vehicle been placed into drive before connecting the scan tool to pull codes, I would have gotten a hard fault code of 67, which means that the neutral/safety switch is working properly. But I didn't do that! In this case, I overlooked a basic test that would have saved me a lot of time. A faulty neutral/safety was the cause of the inoperative speed control. The powertrain control module did not "know" that the transmission was in drive. When working on one of Ford's integrated speed control systems for an inoperative problem, remember this basic test. Before checking anything, first drop the transmission into drive and perform a key-on-engine-off test to see if you get a hard code 67. If the 67 or the three-digit equivalent is not there with the vehicle in drive, you have found the problem -- a faulty neutral/safety switch or circuit. Lesson learned: don't forget those basics!
Acura Legend Cold StartPosted 11/5/1997By Marlowe Peterson
1986-1990 Acura Legends have a nasty habit of not wanting to start on cold mornings. There is a plan I have come to follow whenever I see one of these:
Short trips really aggravate this condition. If the customer only drives short distances and extending the trip is not practical, try using a set of Bosch platinum spark plugs. FR7DPX is the correct application. Because these reach optimum tip temperature faster than most spark plugs, this may be a big help.
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Copyright (c) 1996-2008. Automotive Service Association. All rights reserved.
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