Pages

Friday, April 18, 2014

Dr. Gizmo Column

"Dr. Gizmo"
By Phil Arendt

Warning Light Turns Off Before Shop Can Diagnose   
Question 1
I have a 1998 Audi A6 with 88,000 miles that is in beautiful condition.  Recently, I have been getting an intermittent red ABS light.  My independent shop checked when the light was off and found no problem.  They checked the fluid level and inspected the brake pads and rotors and found everything is ok.  My shop wants to check the ABS system when the light is on.

Whenever the light is on I head for my shop.  As luck would have it the light is off by the time I get there.  I ‘m concerned about using the car when the light is on.  What should I do next?  G.F., email

Answer 1
When the light is on the ABS system likely will not function.  Practice squeeze braking and rapid pumping techniques to control skids until the issue is repaired.  As for the trouble it’s possible there is an air gap issue at one of the wheel sensors.  Also, an electrical connection might be corroded or loose.  Since your car is older, connections and corrosion is an area to heavily weigh and consider. 
Additionally, since your shop has eliminated problems in the brakes a technician might check for a worn wheel bearing.   Excessive wear can increase the air gap at a wheel sensor and turn on the light.

Four-Year-Old Vehicle Nothing But Trouble
Question 2
I have a 2010 GMC Terrain with 50,000 miles.  The timing chain just needed replacement.  Now an anti-lock brake sensor and Stabilitrak sensor are out.  It will cost $1,000 to repair!   I’ve had numerous recalls fixed, including stuck steering.  The engine oil is disappearing.  I could go on and on. 

I live in Minnesota and am scared to death to drive on snow covered roads.  The dealership that works on it said this could be just the beginning of the troubles.  Is this normal for a car this new?  Is there any help from General Motors?  Do you have any suggestions?  G.N., email

Answer 2
Wow your car has been trouble.  It’s not normal.

To find out if General Motors can be of any help call customer service at (855) 238-0773.  When you call, be prepared to provide a detailed vehicle service history.  A representative will need information from repair invoices from all servicing dealer and independent shops.  Also, be prepared to be referred back to your servicing dealership for further assessment of your vehicle.
As for driving in slippery conditions, it’s natural to be cautious and a little frightened, but it’s important to stay calm and focused.  Conscientious drivers grip the steering wheel a little tighter and focus more on driving conditions.  There are exceptions.  The cars you see in a ditch are the result of drivers who failed to recognize driving conditions. 

Stay focused, slow down and keep a good distance away from vehicles in front of you.  If you do, you should be able to control the vehicle even with impaired systems.  After all years ago when cars did not have all the safety features they now have, motorists navigated slick roads safely.  Just because vehicles have systems to help control a vehicle doesn’t mean it won’t slide, skid, fishtail and spin-out on gravel, ice, snow, mud, leaves, rain and oil.  If a vehicle operator exceeds the abilities of a vehicle they could easily lose control and in the blink of an eye collide with a bang or slip into a ditch. 
Once repairs are complete, continue to use common sense during winter driving conditions for a system such as Stability control is not effective if a vehicle operator exceeds limitations.  

Control Module Fails After Battery Replacement
Question 3
I have a 2006 Land Rover LR3.  The battery died so in all my infinite wisdom I jump started it and went to a parts store to buy a new battery.  My car ran fine to and from the parts store.  I did not shut it off until I was home and in my garage. 

I replaced the battery without a hitch.  Unfortunately when I tried to start the engine it started but the transmission did not engage.  I checked all of the fuses and all of them are fine.  There is a message on the dash that says the transmission range is not available.  There are two other messages for special programs and fault programs that are not working. 
I don’t want to have the vehicle towed to a dealer unless I have no other choice.  Did replacing the battery wipe out the engine computer?  Does it need programming?  Did I somehow short out the computer?  What do you think is wrong? R.G., email

Answer 3
If you followed safety practices and did not accidentally short a circuit or reverse polarity, computers should be fine.  Having said this, it appears a control module is causing trouble.  I don’t know which one so it’s time to have the vehicle transported to a shop.  Tests will determine which module is causing trouble, but from what you describe it’s possible a transmission module has failed.

Newly Installed Parts Fail To Repair Condition
Question 4
I have a problem with my 1999 Chevrolet Silverado 1500 with a 5.3 motor that’s been going on for some time.  When accelerating before the engine warms up it loses power and the check engine light turns on.  Once the motor warms up it runs normally.  I replaced the crank sensor because my parts house found 336 in the engine computer.  This did not fix the trouble. 

I also replaced the spark plugs, air filter, fuel filter, fuel pump and fuel pressure regulator.  I also cleaned the m.a.f. sensor.  None of this cured the trouble.  The check engine light turned back on and tests still find code 336. 
I’ve owned the truck since it was new.  It’s my baby and in great condition.  It has 196,000 miles on it and none of the parts I installed had ever been replaced in the past except for the spark plugs and filters.  What do you think is wrong? L.T., email

Answer 4
When a vehicle crosses the 150,000 mile mark it’s a good idea to replace parts such as the fuel pump and water pump as a preventive measure.  These are parts that will fail.  You just don’t know when.  And when they do fail you could be stranded in the middle of nowhere.  Replacing the fuel pump and the pressure regulator at least was a good preventive measure.

Since the condition occurs when the engine is cold, temperature raises suspicions that a sensor such as the engine coolant temperature sensor acts up.  There also is an air temperature sensor within the mass air flow sensor you just cleaned.  I hope you did not scrub the interior of m.a.f. as doing so can damage it. 
Since code PO336 has returned, check the crankshaft sensor circuit for chaffed wiring and poor connections.  It’s also possible the new sensor is defective. 

Another issue might be excessive crankshaft play.  Let’s hope excessive wear of the crankshaft is not the cause but it should be checked to rule that out as a possible cause.  More than likely the crank sensor or circuit is causing this trouble so start troubleshooting there.

Indecision Over Approach To Repair
Question 5
I have a 2008 GMC Acadia with 17,000 miles.  The power steering quit working.  I went to my local shop.  They flushed the system but that did not fix the trouble.  It did improve it a little because when I speed up the engine the power steering is a little easier.  My shop says to fix the trouble they will need to replace the pump and the steering rack.  It’s an expensive job. 

A friend who knows a lot about cars says I should replace the pump.  That might cure the trouble.  My shop says metal contamination in the fluid probably has ruined the steering rack.  What do you think I should do?  D.R., email

Answer 5
There is concern that metal from the pump has damaged the steering rack.  Be this as it may, flushing the system should have removed contamination but since it appears you have driven the vehicle with the failed pump, a flush is needed again. 

At this juncture flush the system and replace the pump.  There is a good chance this will return normal function.  If so, expect that sometime in the future the rack will fail and need replacement.  When it does you might need to replace the pump once again due to contaminated fluid.

Check The Gas 
Question 6
My 2005 Honda Civic with a 1.7 engine stalled and would not stay running after several attempts to restart it.  I had it towed to a repair shop where they have done all kinds of tests but can’t find anything wrong with the engine.  They tell me everything is ok.  There are no codes in the computers.  They said they tested all the computers, replaced the spark plugs and checked ground wires and replaced the air filter.  They told me the spark plugs keep getting wet but don’t know why.  They think it might be caused by an air leak or a fuel mixture sensor but they haven’t found the cause of the trouble. 

The shop is really busy due to the cold weather so they can’t continuously work on my car.  I love my car.  I need it.  Do you have any suggestions?  R.M.B., email

Answer 6
Dump it.  Buy another.  All kidding aside your technician might consider thinking out of the box.  I’m sure he is as frustrated as you.  If tests have not found any malfunction codes at all and the spark plugs are wet he might consider testing the fuel in the tank.  Maybe your car is suffering from contaminated gas.  Perhaps, it’s water or there is too much ethanol.  It could be diesel fuel.  If so, a thorough cleaning of the fuel system and a fresh supply of gas might result in a happy ending to this issue.                

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.  02/03/2014 ® DR. GIZMO © 1989 - Present

No comments:

Post a Comment