Pages

Friday, July 6, 2012

Northwest Herald Dr. Gizmo Column Dated June 29, 2012

06/29/2012

"Dr. Gizmo"
By Phil Arendt
 

Two Door Locks Work, Two Don’t 
Question 1

The door locks on the driver’s side of my 2004 Audi A4 will not lock or unlock from the remote or with the switch.  The passenger side locks work fine. 

I checked the fuses in the panel inside the engine compartment and interior but all the fuses are okay.  Is there a module or switch that I can replace to fix the problem?  A.L., email
 

Answer 1
Guess work might find the trouble but it is a long-shot.  If you have automotive electro-mechanical skills, are adept at do-it-yourselfer projects and have the proper tools including wiring diagrams consider removing the door panel to check power and ground circuits for faults.  Since the fuses are okay, more than likely a switch has failed either in the main control or sensing switch in the door.  It is also possible a wire in the conduit between a door and door frame may have broken. 

Also, it is possible a control module has failed but without a scan tool to check communication between modules, activate devices and retrieve and read trouble codes or program, it is impossible to determine if a module is in trouble.    

Repair depends upon your findings.

Engine Runs Hot Despite Repairs
Question 2

The temperature gauge in my 2003 GMC Sierra with a 6.6-liter diesel engine is hovering around 240 degrees.  I checked the coolant level and it’s right where it should be.  I also had the thermostats replaced but this has not brought down the temperature.  The temperature rises at highway speeds.  When I’m in stop and go traffic the temperature drops to the normal range. 

This trouble began about six months ago.  At that time the water pump was leaking.  The temperature reading was not the issue as I made sure the coolant tank was always full.  A shop replaced the pump and vacuumed all the air out of the system so there is absolutely no air trapped anywhere in the cooling system.  When the temperature rose I returned to the shop and a mechanic tested the gauge and water temperature to make sure the gauge was okay.  It’s reading fine.  In addition ever since the initial work the temperature of the heater has been lower than normal. 

I suspect something is wrong with the water pump.  What do you think is causing the trouble? G.N., email
 

Answer 2
Your suspicions might be on target.  It is possible there is a manufacturing defect in the water pump such as a loose impeller that may be causing reduced coolant flow.   To find out for sure the technician who installed it should consider removing it for examination.  If indeed it has a defect, repairs should be covered under a parts replacement warranty. 

Let’s hope this is the cause of the high temperature readings.  Replacing the pump may be the resolution.


Illuminated Warning Light Is A Mystery
Question 3

I own a 2008 Dodge Ram 1500 with a 4.7-liter engine and automatic transmission.  It has 46,000 miles.  I have owned the truck since it was new.  I follow the factory maintenance schedule for all services.  The truck is in great condition. 

The trouble is the check engine light intermittently turns on.  Over the last year and a half I have taken it to three different repair shops.  Each shop found codes that indicate a problem with an oxygen sensor.  The sensor has been replaced.  One of the exhaust manifolds was replaced and technicians have looked for leaks in the exhaust system and on the engine.  They have done all kinds of tests but nothing they have done has cured the trouble.  With exception of replacing the oxygen sensor and manifold I’m told that everything is within specifications.       

Now I’m at my wits end.  The light is on.  I have taken the truck to yet another repair shop.  I’m told everything is fine.  The mechanic has no idea why the light is on.  Can you help?  P.D., email

Answer 3
Sometimes there are conditions that evade logic, but don’t despair.  From your explanation it appears technicians are attempting to address symptoms associated with fuel trims and oxygen sensors.  A close examination of the wiring for the oxygen sensor circuit is in order.  Perhaps there is a loose pin in a plug.  Maybe there is something on the threads of a sensor that inhibits proper operation.  Something unusual is causing the trouble.  Once the cause is determined the condition will be repaired perhaps in a matter of minutes.

There is one process for you to consider.  If you have basic automotive do-it-yourselfer experience, remove the battery cables from the battery terminals.  Secure the cables tightly together with a clamp, electrical tape or duct tape for about ten minutes.  This will erase learned values in computer modules.  This also will erase radio settings and other personal settings such as seat and mirror memories if your vehicle has these options.  Once time has passed, reinstall the cables to the proper terminals on the battery and drive the vehicle normally.  The powertrain control module that turns on the check engine light will go through a relearn sequence as you drive.  This procedure is a long shot but may reset values and the check engine light may remain off until something authentically slips beyond specifications.

Delayed Start Raises Concern 

Question 4
For about the last month when I start the 3.4-liter engine in my 2001 Chevrolet Monte Carlo I turn the key to start and it may be five seconds before the starter motor activates to crank the engine.  I called a garage about the trouble.  The person who runs the shop did not have any idea what would cause the trouble.  He suggested I bring the car in for diagnosis.  Other than this problem the car runs fine. 

I’m afraid that one day the starter will not crank at all.  Do you know what causes the trouble?  E.S., email

Answer 4
This condition is unusual.  There are many possible causes. 

Perhaps the battery terminals are dirty or corroded.  Maybe one of the bolts on a battery terminal is cross-threaded or loose.  Just maybe there is a loose or corroded ground connection.  Maybe a starter relay has a poor connection or internal fault.  Perhaps the battery has low voltage due to a failing cell or the alternator is not performing as designed.  Maybe the serpentine belt or belt tensioner pulley is excessively worn causing the belt to slip a little.  Perhaps there is a fault in the antitheft system or the powertrain control module has a poor connection.  Maybe the there is a loose connection at the starter motor.  It’s also possible the starter motor has an internal fault.    

There are more possible causes.  Depending upon your expertise you may be able to check for some of these possible causes.  If not, consider giving authorization to an experienced technician who more than likely has all the tools and equipment to diagnose and repair the condition.

Air Conditioner Fails to Work After Repairs
Question 5

I have a Ford Freestyle with an air conditioner that quit working.  I took the vehicle to a repair shop where the mechanic found a leak at a seal on the compressor.  He flushed the system, replaced the compressor, and charged the system but when he was done, the compressor did not engage.  He performed many tests but cannot determine the trouble.  He thinks the system needs reprogramming and suggests that I take the vehicle to a Ford dealer to have the reprogramming work done. 

Does this make sense to you?  Why can’t he do the work?  What do I do if he made a mistake and the Ford garage does not want to repair the trouble?  N.L., email

Answer 5
Dump the vehicle and purchase a new Ford.  Of course I’m kidding.

What you explain does indeed make sense.  More than likely the shop does not have the equipment to program the system.  Apparently, they have the equipment to perform diagnostic tests and activate the compressor to charge the system with refrigerant but the equipment lacks the ability to reprogram the control module.  I’m surprised the technician did not provide an explanation.  Also, often an independent shop will provide the service of taking the vehicle to another shop with advanced equipment.   

At this juncture, take your vehicle to your favorite Ford dealer shop or independent shop that does have the equipment to reprogram the system.  Perhaps your shop has a business relationship with a dealership or another shop that can perform the suggested work. 

If indeed the shop that installed the new compressor did make a mistake or the compressor is defective the shop that installed the part should cover repairs under a warranty policy.

Attempted Repair Fails
Question 6

Recently, the check engine light in my 2005 Ford Thunderbird has occasionally been turning on.  When it is on it feels as though the engine misfires.  When this occurs I can be traveling at highway speed or in town at slow speeds.  It occurs suddenly without any warning.  Once it starts I can travel a few feet with the misfire and light and then everything returns to normal.  Sometimes I might travel a mile or two before the trouble stops.  When the trouble starts the engine feels as though it is running on two cylinders.  It runs awful.  When things return to normal, I might drive days without any problem at all.

I took the car to an auto supply store to have the computer checked.  An employee hooked up a scanner and found code PO2107.  He said the throttle actuator was causing a problem.  I replaced the part and had the computer cleared of codes, but this did not cure the trouble.  Can you help?  L., email

Answer 6
First, it would be a good idea to have the car tested again to determine if the same code has returned or if other codes have popped up.  Address new codes as necessary.  If the original code has returned more work is needed. 

Code PO2107 does indicate trouble in the throttle actuator control processor or associated circuits.  Check the wiring for breaks in the insulation, poor connections such as bent or loose pins in plugs and for broken conductors under insulation.  While it is possible the throttle actuator is defective it is more likely you will find the cause of the trouble in the wiring.

Thanks for all of your great questions.  Dr. Gizmo can’t wait to answer more.
Phil Arendt is a columnist, consultant and A.S.E.-Certified Master Technician.  Readers may send questions to Dr. Gizmo at P.O. Box 548, Cary, IL. 60013 or e-mail address drgizmo@drgizmo.ws. 6/29/2012 ® DR. GIZMO © 1989-2012

No comments:

Post a Comment