Dr. Gizmo Automotive Question and Answer Column

"Dr. Gizmo"

By Phil Arendt

Transmission Fluid Leak Contaminates Computer Module

Question 1

The transmission in my 2002 Mercedes-Benz C230 is not working at all.  When I shift into drive nothing happens.  When I shift into reverse the transmission seems to engage a little but then stops as the car starts to move. 

I had the car towed to my local repair shop because the nearest Mercedes-Benz dealer is about 75 miles away.  My shop did tests but no codes were found in the computer.  They say they might have to replace the transmission or the valves inside it.

The car has 158,000 miles on it.  It’s in great condition.  When the trouble started there were no warning lights on the dash.  No warning lights are on at my shop.  Do you have any suggestions?  S.F., email

Answer 1

The fact that no warning lights illuminated and no malfunction codes were found is unusual but that raises suspicion that there is a computer problem.  Your car has a transmission control module that obviously operates the transmission. 

There have been instances where transmission fluid seeps through an electrical harness attached to the module.  The fluid contaminates and ruins the module.  If this is the problem a new module and some repair to the transmission is necessary.  Ask your shop to consider this as a possible cause to the condition.

Two Systems Impaired By One Failing Part

Question 2

The power steering in my 2005 Chevrolet Silverado 2500 with a diesel engine makes noise.  I hear the noise when turning especially in tight turns.  Also, once in a while when coming to a stop the brake pedal feels soft. 

When the noise started I checked the fluid in the power steering tank.  It was full.

A friend that knows about cars said that sometimes changing the power steering fluid can stop the noise.  I had the fluid flushed but the noise continues. 

What do you suggest I do next?  R.D., email

Answer 2

Trade it for a Smart for Two.  All kidding aside, the power steering and power brake system in your vehicle receives hydraulic pressure from the power steering pump.  When there is an internal problem in the pump it affects both systems.  That’s probably why the brake pedal doesn’t feel normal at times.

To fix the trouble might require replacement of the power steering hydraulic pump and the hydro-boost unit for the power brakes.  When you take the vehicle to a repair shop they likely will check the operation of these parts.  Repair depends upon technician findings.

Blinkers On The Fritz

Question 3

I have a 1997 Chevrolet Tahoe with 213,000 miles.  Recently I've had issues with the blinkers.  Sometimes they work and sometimes not.  Usually, they'll start with the normal frequency and then might slow down or totally stop blinking.  Sometimes when they stop, since I still have the lever on, they start up again.  It happens in either direction.

My grandson and I have done some checks.  When they're working, even slowly, the tail lights illuminate with the same sequence.  
Do you have any ideas?  Is this a major repair?  M.D.M., Woodbury, Minn.

Answer 3

Yes, I do have ideas.  I think we should once again send astronauts to the moon, this time in a car that can land on the moon and return to earth.  And no, this is not a major repair. 

Sometimes a condition such as this is caused by low battery voltage.  Make sure the battery is capable of holding a full charge.  Have it tested.  Also, the terminals and cable ends need to be clean and shiny inside and out.

If the battery and cables are ok, the trouble might be caused by a faulty flasher relay.  Replacing it might be a lasting cure. 

These suggestions won’t cost an arm and a leg.

No Such Thing As A Silly Question

Question 4

This is not a question about a problem with my car.  Perhaps this is a silly question but when we build vehicles that are sold in countries with the steering wheel on the passenger side, do manufactures have to make different engines to accommodate the steering?  D.A., email

Answer 4

Generally, the basic engines are the same as they are in the good old United States of America.  Obviously the entire vehicle needs to comply with another country’s laws.  Generally, to accommodate steering components car makers move parts that bolt to the engine.  They also move parts around in the engine bay so the steering column fits nicely on the right side.  Of course the instrument panel, clutch, gas and brake pedals move to the right side as well but the engine block that is used here generally is the same overseas.  This is why you might find threaded holes in engines that are not in use.

Some Things Are Secret

Question 5

I have a 1997 Chevrolet Lumina that is having a problem with the factory antitheft system.  Is it possible to bypass the system?  What needs to be done?  R.W., email

Answer 5

First of all I can’t divulge the procedure to bypass the system in this column due to space.  It can be done.  However, there might be an individual who is itching to make a quick buck on a stolen vehicle.  Additionally, it more than likely would cost more to bypass the system than to repair it. 

Award the repair to your favorite shop.  Be sure to receive an estimate before authorizing any work.

First Things First

Question 6

I have a 1996 Buick Riviera with a 3.8-liter engine and nearly 300,000 miles.  I love this car.  It’s in great condition.  I take great care of it. 

The trouble is the ABS light is on and the heater and air conditioner control quit working.  I went to a repair shop that has been taking care of it for many years.  They do fantastic work.  They did some tests.  Their diagnostic scanner tool will not communicate with the computers that control these systems.  They say that before they can fix the car they need to restore communication with the computers.

I’m not going to get rid of my car.  It’s my baby.  Would replacing the modules fix the problems or is it more complicated than just replacing some parts?  N.R.M., email

Answer 6

Congratulations for rolling nearly 300,000 miles.  That’s further than the distance between the earth and moon.  This is all due to the care you give your baby.  Also, it is great that you give your shop a thumbs-up.  

As for replacing parts, communication issues often are caused by open circuits.  There might be a broken wire or faulty ground connection.  If this is the problem installing new modules will not fix the trouble. 

Your shop needs to troubleshoot the circuits.  If the circuits are ok, then it is time to consider replacing modules.         

      

Thanks 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.  10/20/2014 ® DR. GIZMO © 1989 - Present