Dr. Gizmo Column

"Dr. Gizmo"

By Phil Arendt

 

Good Samaritan In Trouble

Question 1

Over the weekend I used my 2005 Buick Rendezvous to jump start a car.  Over the years I have done this many times without any trouble until now.  While the other car was cranking my car shut off.  The other car started.  Since then the dash warning lights do not turn on and the engine starts and stalls. I had the car towed to a repair shop.  The manager thinks the engine control module and body module are fried due to a power surge or improper jump start procedure.  He won’t know for sure what is wrong until his technician tests the vehicle. I know I followed the right jump start procedure.  What do you think is wrong with my car?  D.R., email   Answer 1 Your aid to a disabled vehicle should be rewarded and not punished with damage to your car.  The encountered trouble is likely due to a power surge.  There is nothing you could have done to prevent this except not provide assistance.  Consider purchasing a portable jumper box from your local auto supply store so in the future you won’t have to use your vehicle as an emergency road service vehicle. As for the trouble in your vehicle.  It is possible for a module to suffer from a power surge but modules are protected by fuses so more than likely a fuse did its job and opened the circuit to protect modules. Since your engine runs, albeit not well, more than likely the engine control module is okay.  More than likely the body control module that communicates with the engine control module and manages the dash warning lights is suffering from the event.  A check of the circuit shows two fuses are in module’s circuit.  Ask your technician to consider this when he begins trouble shooting.   Electrical Problem Or Overhaul Question 2 I have a 2007 Chevrolet Silverado 1500 LTZ with a transmission that shifts from first to second gear but it will not shift into third or fourth gears.  I went to a repair shop where the mechanic found a malfunction code for a faulty speed sensor.  He replaced the sensor but the transmission still does not shift out of second gear.  Now he thinks it needs an overhaul and wants to send the truck to a transmission shop for another opinion.  My truck has 107,000 miles.  It’s in great condition.  I have followed the factory maintenance schedule to the letter having all recommended services done on time.  This is my third Silverado.  I have never had any trouble with them.  I usually keep them 200,000 miles.  Do you think the transmission is shot?  N.B.R., email   Answer 2 I understand your concern.  After all a trans overhaul is expensive but it sure beats the expensive of a new truck. It is possible there is a problem in the vehicle speed sensor circuit that needs repair.  Perhaps a fresh look into the trouble by another technician at another shop will find an issue in the circuit and repair it.  If there is no problem found in the circuit, the sensor relies on input from inside the transmission.  If this is the cause the transmission needs disassembly.  This will require replacement of seals and worn parts such as clutch plates. This is an overhaul.  Let’s hope an issue in the speed sensor circuit is the cause of all the trouble.   Power Steering Quit A Year Ago Question 3 The power steering in my 2004 Audi S4 Cabriolet quit working a month after I purchased it about a year ago.  At that time I went to a repair shop where they checked the pressure on the pump and flushed the system.  They told me the pump is working so the trouble must be in a solenoid or steering rack.  They said the system does not have the capability to be tested by a scan tool so they need to remove the steering rack to determine if the solenoid has a problem.  I did not drive the vehicle all winter.  I would like to have this problem repaired before warm weather returns.  I trust my shop but I’m leaning toward taking this problem to a dealership.  What do you suggest?  L.B., email   Answer 3 This decision is strictly up to you.  It appears your shop is on the right track but unless they specialize in repairing Audis there is no place better equipped to handle repairs than an Audi dealership.  I’m not saying your shop can’t handle the repair, but it is likely a dealer has more experience and the specialized equipment tools to diagnose and repair the trouble. Heater Problem Has Many Possible Causes Question 4 For the last week or so the heater in my 2005 Chrysler 300 is not blowing hot air all of the time.  When stopped at a light or in traffic the heater cools down.  Once I’m cruising the heater temperature goes up.  The engine temperature gauge on my dash varies as well.  It shows about 190 degrees when the engine idles and about 220 when traveling.  This has never happened before. I checked the level of antifreeze in the tank.  It was down but just below the add mark.  I added antifreeze to the full mark.  This did not change the performance of the heater.  I went to my repair shop.  A mechanic checked over the engine.  He says there must be an internal leak because there is white foam in the valve covers.  He thinks a head gasket is leaking and wants to tear apart the engine.  Does this seem right to you?  D.L., email Answer 4 It’s possible a cylinder head gasket is leaking but it’s not time to tear apart the engine yet.  Generally a head gasket springs a leak after an overheating event.  It does not appear that your car has encountered this condition. Additionally, white foam in the valve covers can develop due to fluctuations in ambient temperature and can form overnight.  Before tearing into the engine consider seeking a second opinion at a different shop.  Also, it’s possible the thermostat has a fault and needs replacement.  Additionally, it is possible there is a restriction in the heater core or just maybe air is trapped in the system.  In addition to all of these suggestions it is feasible a faulty water pump is the cause of the trouble.   Misfire Caused By Lean Fuel Mixture Question 5 My 2008 Jeep Wrangler has 155,000 miles and a 3.8-liter engine that misfires.  About a week ago the check engine light turned on and the engine began to misfire.  I went to a repair shop.  They found multiple misfire codes and suggested a tune-up.  I replaced the spark plugs myself but this has not cured the trouble.  I returned to the repair shop.  Now they say the engine is running too lean but don’t know why after several tests.  Do you have any suggestions?  G.G., email   Answer 5 Sure.  It’s time to dump the Jeep.  All kidding aside, lean fuel mixture problems have many causes including air leaks from cracks in manifolds to loose vacuum lines.  I’m sure your shop is looking at every possible cause using equipment such as a smoke machine to locate leaks.  One problem they may not consider is a failing fuel pump.  I’m not certain but I don’t think your engine has a port to check fuel pressure and volume.  If this is the case a technician will need to fabricate a test to determine if the fuel pump is the cause of the condition.  Once fuel pressure and volume is determined your shop will know if the pump needs replacement.  After all if the engine is starving for fuel tests will indicate a lean fuel mixture and lean mixtures cause an engine to misfire.   Warranty Transmission Repair On The Horizon  Question 6 Six months ago the automatic transmission in my 1995 Mitsubishi Eclipse failed.  My shop installed a remanufactured transmission.  Now the transmission is doing the same thing the old transmission did before it completely failed.  I called my repair shop about the trouble.  They told me to come in so they can check out the problem.  I can be driving along at 45 mph and the transmission will suddenly shift from a high gear to a lower gear without any warning.  It’s feels like I’m stomping on the brakes when I’m not touching the brake pedal and the engine revs up real high.  Do you think the transmission needs replacement again?  Should I take it to another repair shop?  C.L., email   Answer 6 Consider going back to the shop that installed the remanufactured transmission.  More than likely the unit is covered at least by a 12 month or 12,000 mile warranty.  If it needs replacement again within the 12/12 warranty period you should not be charged for another transmission if indeed it has a fault. Additionally, it is possible there is another cause for the trouble but you won’t know until your shop performs tests. If the transmission is the cause of the problem and you authorize another shop to perform work, it is more likely you will pay for transmission repairs.  Let’s avoid that expense.

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@hotmail.com 04/08/2013 ® DR. GIZMO © 1989-Present