Diagnosing Pulse-Width Modulated PWM Fuel Pumps
Just this summer, I experienced a situation in which the fuel pump had been replaced four different times on a single vehicle with no result because the various repair shops attempting to repair the vehicle didn’t understand how to diagnose a pulse-modulated fuel delivery system. Here are five things you should know about diagnosing them.
2010 Jeep Wrangler: Transmission Stuck In Second Gear
The 2010 Wrangler’s transmission solenoids are powered through its totally integrated power module (TIPM), which is a fuse and relay box with a logic board that controls most body electrical functions.
Chevy S-10 Truck: Slow Acceleration When Cold
This problem was referred to me by my local transmission shop. The elderly owner’s complaint was that the S-10 “accelerated kind of slow when cold.” Further questioning revealed that, after the transmission warmed up and the ignition was cycled off/on, the S-10 would accelerate normally.
Timing Chains In Hyundai Engines
Although Hyundai uses a single timing belt on its 2.7L V6 engines, its 3.3L, double-overhead camshaft engine is equipped with one timing chain for each camshaft and one drive chain for the oil pump. At first glance, a timing chain design allows engineers to shorten the overall length of the engine and reduce rotating friction.
Wiring Harness Diagnostics Dodge Sebring
This month’s Diagnostic Dilemma begins with a 2004 Dodge Sebring, 2.7-liter VIN R. The owner had recovered codes P0118 (ECT), P0073 (ambient temp), P0122 (throttle position), P0123 (throttle position), P0340 (CMP), P0335 (CKP), P0129 (MAP/Baro) and P0113 (intake air).
Trailer Brakes: Connector Outlet Electrical Diagnostics
Gary Goms goes over two case studies this month involving trailers. The electric brakes on one do not function, and the brakes on another activate when the parking light turns on. Learn how bad wiring and damage from rodents can cause these issues.
GDI System Service
Because gasoline direct injection (GDI) was widely introduced during the 1990s, the configuration of any GDI system will vary according to age and application.
Subaru Pulse-Width Modulated Fuel Pumps
I think it might have been a 2003 Subaru WRX, but it was parked in front of my local Subaru specialist’s shop after going on its fourth fuel pump replacement from other shops in less than six months. Both the Subaru specialist and I agreed that fuel pump failures on Subarus were relatively rare, so the previous repair shops had obviously overlooked some very important details.
Fuel Trim And AFR Sensors
Fuel trims are a difficult topic to cover in a matter of a few pages. But this summer, an old friend and former teaching partner arrived at our local car show with the check engine light illuminated on his 2004 Holden Monaro, which was imported from Australia and rebadged and sold in the U.S.
Horn Honks When Door Is Opened
This month’s Diagnostic Dilemma begins with a 2012 Jeep Rubicon that honked the horn each time a door was opened. The call came from a small-fleet diesel tech who also gets his share of his business owners’ personal vehicle problems. Doing some information gathering, we discovered that the horn honked when the door was opened or when the exterior or interior lighting was activated.
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.
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 ’98 Wrangler was slow-starting in the morning.
