Pulling Codes: The Story of U1016
This Pulling Codes article will center on issues involving the powertrain control module (PCM) talking to your scan tool. In many states, this is the controller our scan tool needs to talk to in order to determine if the correct number of monitors has run and passed. It’s interesting to note that there appears to be two modes of failure in terms of communication.
Diagnostic Dilemmas: When Over-Voltages Electrocute PCMs
During the past nine months, I’ve had three instances of powertrain control module (PCM) failures on Jeep Wrangler vehicles that were evidently caused by an over-voltage condition. The first case involved an owner who requested that a local shop replace the fuel pump because his 1998 Wrangler was slow-starting in the morning. The shop found the pump pressure was marginal and replaced the pump. Because the Jeep still had the problem, the owner complained about the fuel pump, first to the shop and then to the local jobber supplying the pump.
Tech Tip: Nissan DTC P0420 Stored in ECM
If you confirm DTC P0420 (Catalyst System Efficiency Below Threshold) is stored in the ECM, determine if this bulletin applies by checking the ECM part number.
Tech Tip: Nissan’s Engine Idle Speed is 25 RPM too High
If you confirm the idle, in Park or Neutral, is more than 25 rpm above specification (with the engine warm), and/or DTC P0507 (ISC System) is stored, this incident may be the result of recent cleaning or replacement of the throttle body. The vehicle “in-use” learned idle may be higher after throttle body deposits are reduced (by cleaning or replacement).
Ford Reflash Tech Tip: PC Settings
So, you’ve just finished up a Ford, and you’re about to try and start it up. However, it needs programmed. You’ve decided to use a J2534 tool, but there are certain things you’ll need to consider before purchasing that subscription at www.motorcraftservice.com.
Gonzo’s Toolbox: Second Guessing a Second Opinion
Who out there knows everything about automotive repair? Who out there has seen it all, and wouldn’t be surprised if something so common to do now turns out to be not so common? Well, one thing is for sure, it is not me. I learn something new about this crazy car business every day. Especially when it comes to the electronics in today’s cars.
Diagnostic Solutions: Diagnosing Misfires
Although diagnosing misfires can be a tough assignment for any driveability technician, the diagnosis can be made much simpler if he understands the basics of misfire diagnosis. For example, when the first OBD II misfire monitor was first introduced in 1996, technicians were puzzled by problems with false misfire diagnostic trouble codes (DTCs). Case in point, vehicles being driven on washboard dirt roads began recording false misfires.
Tech Tip: VW’s MIL is On, with DTCs P0087/P1093 or P2293
This condition could be caused by excessive wear of the intake camshaft lobe that drives the high pressure fuel pump. The wear limits maximum pump piston lift, causing fuel rail pressure fluctuations. The wear on the camshaft lobe can also lead to wear on the base of the high pressure fuel pump cam follower.
Solving Common Honda Driveability Problems
One of the common check engine light problems you’ll encounter on Hondas is a misfire code with no apparent misfire. Many times, this problem will be traced back to tight valve lash. Obviously, a tight valve will pass the audible test every time. But, it’s the tight valves that will set the check engine light in the best case, and if it’s ignored long enough you’ll be looking at a low-compression situation caused by a burnt valve.
Diagostic Dilemmas: Lost in ‘The Diagnostic Woods’
This real-world case study of a 2002 Chevy S-10 pickup, a 1995 Buick and a 1995 Lincoln Town Car illustrates why “chasing” trouble codes can get you lost in the Diagnostic Woods.
Tech Feature: Courage Under Misfire
Generally, when a customer brings a vehicle into a shop that has a misfire concern, they will describe it as bucking, jerking or loss of power. They also may describe it, depending on the cause, as a jerking when they take off from a start, but smoothes out once the vehicle gets moving. They may tell you the check engine light has been flashing.
Tech Tip: Nissan Engine Will Not Crank with Outside Temperature Below 10
A no crank condition may call for replacement of the Intelligent Power Distribution Module-IPDM.