The Law of Unintended Consequences Seems to Trip up the Unwary Or Unprepared Every Time. It's Well Worth Finding out What

FOREIGN SERVICE APRIL 2015v2_Layout 1 3/18/15 11:30 AM Page 1 Foreign Service

The law of unintended consequences seems to trip up the unwary or unprepared every time. It’s well worth finding out what you need to know before disconnecting a vehicle battery.

ears ago, we disconnected bat- must scramble to solve these unexpected teries without giving it a second problems before the customer returns to pick thought. Usually, the only ad- up the vehicle. When you’re rushing to do verse consequences were losing this, you can complicate matters by making Dan the radio station presets and the more mistakes. correct time on the dashboard Ultimately, you may find that backup pow- Marinucci clock. But today, the side effects of removing er (using a good automotive battery or a pro- Ya battery cable may be both costly and con- fessional power supply) is cheap insurance. [email protected] fusing. This month I’ll discuss strange symp- It’s certainly simpler and faster than coping toms you may encounter after disconnecting with unpleasant surprises after you’ve had to the battery on some import vehicles. disconnect a battery. Back in my February Mind you, many imports tolerate “battery 2015 column, I noted several details about disconnect” remarkably well. If the on-board connecting backup power. You usually can’t electronics have to recover after you recon- connect to the cigarette lighter socket or a nect the battery, they do so quickly—if not 12V power port. Typically, these are not live immediately. However, experience also has until you turn on the ignition switch. Second, shown that oddball problems may happen af- you can quickly and safely apply backup pow- ter you reconnect the battery. As a result, you er via the DLC connector with one of the newer DLC-specific breakout box tools. I cit- ed several examples of these on page 9 of the February issue. Our colleague John Rogers operates JWR Automotive Diagnostics, a mobile diagnostic service on Long Island, New York. His clien- tele consists of professional repair shops. The first examples of battery-disconnect symp- toms that Rogers cited were on Nissan’s elec- tronic throttle control (ETC) system. The symptoms were DTC P0507 coupled with a high idle speed or a fluctuating idle. This DTC’s definition is “idle control system RPM higher than expected.” Rogers emphasized that if a battery disconnect is going to upset a Nissan ETC, it usually occurs on vehicles older than about 2007. “On 2007 and newer Nissans, the ETC seems to be much more Photo: Dan Marinucci Dan Photo: tolerant of a disconnected battery,” he said. Some techs clean the electronic throttle blade and bore with tools such as a bottle brush (shown here) Rogers explained that performing a proper or toothbrush. Others use a moistened shop towel. idle air volume learn (IAVL) procedure is the Regardless of the cleaning tool selected, take great way to eliminate the P0507 as well as the idle care to use the minimum amount of throttle cleaner speed problems. One way to do the IAVL is necessary. Otherwise, you risk getting cleaning liquid in the throttle’s electronics and ruining them. Turn with an OEM Nissan scan tool such as the the ignition on, engine off. Then use a proper throt- Consult II or an aftermarket scanner tle tool to keep the gas pedal floored. These steps equipped with that function. The other way cue the ECM to hold the throttle blade open for you. is by carefully following the “relearn” steps continued on page 12

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outlined in Nissan’s service litera- Maxima. The techs at a shop could- ture. (This scannerless approach is n’t figure out why this Maxima’s au- detailed in Nissan service bulletin tomatic transmission was shifting so No. NTB05-067.) Don’t shortcut harshly. They called on Rogers to any of the preliminary steps, investigate the symptom. Sure Rogers cautioned, or this relearn enough, a road test confirmed the QUALITY. procedure simply won’t work. harsh shifts. The detail they initial- These steps include making sure ly forgot to pass on to Rogers was the throttle blade and bore are that this Maxima had sat with a clean, bringing both coolant and stone-dead battery for a long, long ATF temperatures up to the mini- time. The effect of the dead battery mum required values, shutting off was the same as that of a discon- accessories, keeping the steering nected battery. wheel centered, etc. Once again, Rogers found an ini- Forewarned is forearmed, read- tialization or relearn procedure for ers. Rogers said he’s encountered this computer-controlled trans in pre-2007 Nissan ETC systems on the work support category of the which he couldn’t perform the Consult II scanner. He performed IAVL procedure without using the this procedure and began road-test- Consult II. ing the car. Not only did shift quali- ty improve dramatically after the Nissan Steering Angle relearn, it got better and better as Sensor Snafu he drove the car. Indeed, Rogers Rogers said that another potential gambled on the solution to this victim of battery disconnect is the very oddball condition. But the steering angle sensor on Nissan gamble paid off, saving untold Pathfinders equipped with the ve- time, money and aggravation for hicle dynamic control (VDC) sys- everyone involved with this car. tem. Basically, the VDC system Last but not least for this month, combines the ABS and traction watch out for idle control problems control systems. Other automakers on some Toyota vehicles equipped might call the equivalent setup a with electronic throttle control. vehicle stability control system. Rogers said he’s encountered symp- Suppose someone disconnects toms such as an extremely low idle and then reconnects the battery on speed and a start & stall on these one of these Pathfinders. In that Toyotas after someone disconnect- case, sometimes a VDC OFF warn- ed the battery. First, check for a ing light appears on the instrument badly varnished or “coked” throttle panel. At the same time, DTC blade and bore. Where necessary, C1163 is stored in the ABS/TCS carefully clean the blade and bore. module. This code’s definition may Take special care not to get any be listed as “steering angle safe cleaning liquid into the throttle mode inspection” or “steering angle shaft bore. learn undone.” Anyway, eliminating If the throttle assembly is clean, this trouble code and resetting the Rogers said, usually all you have to steering angle sensor requires an do is disconnect the battery cables OEM scan tool or one that’s got again, reconnect them to the bat- strong Nissan-specific capabilities. tery and restart the engine. (It may Rogers said the steering angle sen- stall one more time here.) Then the sor reset procedure can be found in idle speed will normalize after you the tool’s “work support” category restart the engine. under the ABS module heading. Okay, I’ve run out of room here Some readers probably get tired for this month. Be sure to tune in of hearing me harp about vehicle next month when I’ll discuss bat- history. However, getting an accu- tery-disconnect consequences on rate vehicle history was vital to vehicles such as VW and Volvo. I’ll solving shifting problems on a 2005 look for you then. Circle #12

12 April 2015