Throttle-By-Wire Diagnostics
Throttle-by-wire is a standard feature on most late-model vehicles. Most of the time, the system is very reliable and usually does not fail completely, thereby leaving the driver stranded. Instead it “limps” along, letting the driver move at idle or at a restricted speed. Swapping a throttle-by-wire unit for a new unit hoping to resolve a code or limp-mode problem is not an option due to the high price and strict manufacturer return policies. Being able to think through and diagnose a throttle-by-wire problem is critical to working on late-model vehicles.
Oxygen Sensor Replacement Basics
Did you know replacing worn or failed oxygen sensors is the best way to protect expensive three-way catalysts or catalytic converters? Failure to replace failed oxygen sensors at the earliest sign of a problem, usually indicated by an illuminated check engine light, can cause premature failure of three-way catalysts or catalytic converters.
Parasitic Drain II: Jeep Grand Cherokee
As a general rule, a “parasitic drain” of less than 30 milliamps (mA) is normal for most vehicles 15 years old and newer. Keeping in mind that most manufacturers now publish parasitic drain values, let’s assume that a battery drain exceeding 50 mA is cause for concern.
Clicking Noise When Shifting Between Reverse And Drive Or On Hard Acceleration
Some customers may comment on a clicking-type noise coming from the front of the vehicle when shifting between reverse and drive or on a hard acceleration. Add a washer between the front wheel drive shaft and the bearing hub assembly using the procedure in this Tech Tip.
Ultimate Underhood: Economy Runs
The Mobil Oil Economy Run was a real world fuel efficiency test before fuel efficiency numbers were posted on window stickers. The event ran for 32 years until it was abruptly canceled in 1968.
Lexus: Notchy Steering Wheel at Highway Speeds
Some Lexus vehicles may exhibit an intermittent non-binding notchy steering feel and/or the steering wheel will not smoothly self-center when driving at highway speeds. This condition may occur when changing lanes or when coming out of long, sweeping turns at highway speeds.
Stretch Belts: Using The Right Tools
Stretching the belt may seem counterintuitive after everything you have been told about serpentine belts. But stretching the belt with the right tools is often the only way stretch belts can be installed.
Jeep Tech Tip: 4WD Light On, DTC C140F Set
Customers may indicate that the “Service 4WD” indicator in the instrument cluster is illuminated. They may also indicate that the transfer case will not shift from 4WD High, 4WD Low, and/or Neutral once the lamp is illuminated. Further investigation identifies that a Diagnostic Trouble Code C140F is stored or active in the Final Drive Control Modules (FDCM) memory.
GM TPMS Tips
Shops should use a TPMS tool that can reset the sensor positions after rotation. There is a method in the owner’s manual to “match” the sensors that involves deflating a tire for eight seconds. On vehicles without a driver information center, you will know you have a code set if you turn the key on, without starting the engine, and the TPMS light blinks for one minute and then stays on solid. If that occurs, a TPMS system problem exists and the system will have set a DTC.
Saturn Tech Tip: Vehicle Fails Emissions Tests
State emissions tests need to be done, but when a vehicle does not pass the test the first time, where do you look? This Real Fix provides multiple diagnostic procedures that could lead you to the fault. Kiss that ugly engine coolant temperature sensor wiring harness damage goodbye and ensure that the Saturn passes the emissions test with flying colors.
GF-6 Oil Specification: What It Means For Your Shop
The Obama Administration finalized fuel economy standards in 2012 designed to increase fuel efficiency standards to 54.5 mpg for passenger cars and light-truck applications by 2025. This push for greater efficiency, reduced greenhouse gas emissions and better energy security set in motion the need for an improved motor oil capable of superior lubricant performance. The proposed International Lubricants Standardization and Approval Committee (ILSAC) GF-6 specification would answer the industry’s need for this more robust motor oil.
Check Out The May Issue Of Underhood Service Magazine
The digital version of the May issue of Underhood Service is available on-line. Click to access the easy-to-view digital version that features articles on automatic temperature sensors, over-voltaged PCMs, TPMS, ignition, a host of Tech Tips, and more!
