Dr. Gizmo Column

"Dr. Gizmo"

By Phil Arendt

Rear Gate Won’t Unlock  

Question 1

I have a 2004 Buick Rendezvous.  The rear tailgate only opens with "REAR" button on the FOB.  At one time it opened like the rest of the doors with the "UNLOCK" button.  My sister has a 2006 Rendezvous with the same problem.  What’s up?  R.W., email

Answer 1

It’s possible the cure will be different for both vehicles, but maybe it will.  Since the rear gate opens with the key fobs in your vehicle and sister’s cruiser the trouble likely is caused by a fault in the body control module.  It appears the circuit is sound but it is advisable to check to make sure.

Tests of the circuit and module will find the cause of the trouble.  If the trouble is caused by a faulty module, replacement is the cure.

New Spark Plugs Fail To Smooth Idle

Question 2

The 2.3-liter motor in my 1993 Ford Mustang idles rough.  When cruising, the motor runs fine. 

I went to an auto parts store where tests did not find any computer codes.  I removed the spark plugs and found the electrodes on both spark plugs in cylinder two were burnt.  I replaced all of the spark plugs but the motor still runs rough at an idle.

I purchased the vehicle three years ago.  Presently, it has 55,000 miles.  The car is in like-new condition.  What should I check next?  D.J., email

Answer 2

Consider checking the 2016 Ford Shelby Mustang GT350R.  I think you will forget all about the 2.3-liter engine in your stang when you ignite 526 horsepower in the Shelby.  All kidding aside, the trouble might be caused by a lean fuel mixture especially in cylinder two.  Causes for such a condition might be related to a vacuum leak or perhaps valve train issues.  It’s also possible fuel system trouble such as low pressure or volume might be the cause. 

It’s time to send your ailing pony to a technician for diagnostic tests.

Suspension Leveling System Fails After Tire Rotation

Question 3

Recently, I took my 2007 Mercedes-Benz E550 to a local tire shop to have the tires rotated while I waited.  When I got home I noticed that rear of the vehicle was lower than normal.  I called the tire shop about the trouble.  They said to bring it back for an inspection.  Did they do something to the rear suspension?  M.D., email

Answer 3

If you are asking if they sabotaged your vehicle, I doubt it.  Also, a tire rotation service does not involve tinkering with the suspension. 

Your vehicle is equipped with a ride leveling system.  It’s possible that a sensor on the rear suspension has failed.  Also, there is linkage connected to the ride leveling sensor that might have disconnected when the vehicle was raised for the tire rotation. 

A visual inspection of the linkage and tests of the sensor and circuit should find the cause of the condition.

Top Fails To Go Down

Question 4

The top in my 1997 BMW 328i goes down about half way and then stops.  Usually the trunk opens for the top to go all the way down but it does not open.

With warm weather here I need to put the top down.  It worked without any problem last fall.  Is there a simple fix for this problem?  S.M., email

Answer 4

The system has motors that have micro switches within them.  It’s possible a micro switch has failed which would require replacing a motor.  It’s also possible there is a broken wire.  Additionally, a loose or corroded plug could cause this problem. 

Considering vehicle age and the number of moving parts to the top system and trunk a close examination of the wiring might find a broken wire.  If so, a simple repair will once again let the sun shine upon you.      

Computer Needs To Sync New Parts 

Question 5

The 4.0-liter engine in my 2005 Jeep Wrangler hesitates and cuts out when accelerating.  Also, the check engine light is on.

I do a lot of repairs on my vehicles so I went to an auto supply store for tests.  They found code P0344 for the cam sensor.  I replaced the sensor but this did not cure the trouble.  My partsman did another test and found the same code.  He exchanged the sensor but the replacement did not cure the trouble.  Now he says that the engine module might need flashing.  He suggested that I go to a dealer to have the work done.  Is this necessary or is there another problem?  B.K., email

Answer 5

There might be two issues for this condition.  One issue is the part.  More than likely the newly installed part is an aftermarket part.  Aftermarket parts are supposed to meet or exceed original equipment manufacturer specifications but sometimes they don’t perform as well as OEM.  Consider installing an original equipment part.  It might be the cure.

The second possible issue is the camshaft and crankshaft sensors might need to go through a relearn process.  To do this a technician must connect a scan tool to the vehicle and follow relearn procedures.  In some cases a generic scan tool is capable of performing the procedure along with a test drive but it might be necessary to use a manufacture specific tool called a DRB that some independent shops have in their arsenal of equipment.  If you can’t find an independent shop with a DRB, you’ll need to visit a dealership for the work.

No Spy Needed To Break Code

Question 6

I read your column every week.  You have helped me more than once, but I have a suggestion.  Frequently, questions refer to codes that have been retrieved from a module.  You explain codes but I would like to know if there is a way to decipher a code when I read your column.  Is there an easy way to do that?  R.G., email

Answer 6

You’ll need a team of government spies and code breakers to decipher malfunction codes.  All kidding aside, if you type a code into the search engine of your internet browser you’ll find a ton of information.  It won’t be specific to your vehicle but it will provide generic information.

To help take some of the mystery out of a code let’s look at code P0344 from the last question that indicates an issue with the camshaft position sensor.  P relates to a powertrain issue.  If it was B, C or U the code would relate to body, chassis or network problems.  The zero following the P denotes a generic code.  If the numeral is one instead of zero, one denotes a manufacture specific code.  The numeral three following the zero indicates an ignition system problem.  Number forty-four following the ignition system code indicates a component, section of a system or specific fault. 

Now that you have this knowledge, all you’ll need is a decoder ring, CIA operative and Dr. Gizmo to help break codes.                             

                                               

Thank you for all the 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@hotmail.com.  05/2016 ® DR. GIZMO © 1989 - Present