Dr. Gizmo Solves Your Car Troubles: Pt. 5 Page 2

January 14, 2010

1997 Ford Mustang

I left the dealer with $69 less in my pocket.  I also felt OK about what I had learned except for the part about their not being able to distinguish which unit needed replacement.  I thought diagnostic tools would be able to do that.  If I decide to do the work, I would replace the right side original assembly first. Then, I would perform tests before proceeding.  I also fear that since both units seem to be acting in unison, that the control unit is the culprit.  What is your opinion about how I should proceed?  J.D.W., email

Answer 2

You have many concerns.  Tests by the technician are not cut and dry.  Sophisticated diagnostic equipment used by a technician does leave room for interpretation.  It does not always pinpoint the source of a problem but often tells a technician to focus in a certain area such as a circuit.  Then a technician performs more tests such as individual tests on wheel sensors.  Since corrosion and dirt often impairs wheels sensors, it is difficult to determine if a failed sensor causes faulty signals sent to the control module or if corrosion and dirt is the culprit.

Since it appears you will be tackling this repair on your own, your approach to repair makes sense.  Replace the oldest unit and if needed replace the part with fewer miles of use.

No Heat For Driver

Question 3

The heater in my 1999 Buick Park Avenue blows cold on the drivers side and hot on the passengers side.  My wife is very happy with the heat on her side but while she is nice and warm Im freezing.

I called my reliable independent shop about the trouble.  The manager told me that his technician might have to tear apart the dash.

Is this necessary?  R.P., email

Answer 3

This is simple.  Ask your wife to drive.  Then you will be toasty warm.  All kidding aside it is likely that the shop manager overstated what action his technician will do when he troubleshoots the problem.  Sure, he likely will need to remove components from the dash but the process will not require the use of a chainsaw and cutting torch.

A stuck or broken blend door in the ducts might cause the trouble.  Maybe an actuator motor needs replacement.  Perhaps the control head needs replacement.  Tests of the control head and air blend doors will determine the course of action.

Before you take the car to the repair shop, empty the glove compartment as the technician likely will need to remove it.  In addition, if you have any accessories attached to the vents and on the front of the dash, remove them as they will slow down the repair and might be damaged.

Fuel Injection Problem Disables Vehicle On Roadside

Question 4

My 1999 Buick Regal with a 3.8-liter engine died while driving down the road.  It cranks fine, but does not start.  Im an avid do-it-yourselfer and have done most of the work on this car since it was new.  However, Im stuck on this one.

The engine has spark and fuel.  The only problem I see while doing tests is that the injectors do not seem to be working.  Ive checked the fuel pressure, cam and crank sensors.  Everything seems okay except the injectors.  I thought the trouble was a failed engine control module but installation of a replacement module did not cure the trouble.

My car looks and usually runs like new.  Now it is just sitting in my garage.  What could cause this problem? J.J., email

Answer 4

Since you are an avid do-it-yourselfer, it is time to check the voltage at the wires to the powertrain control module and ground connections.  There appears to be a fault somewhere in the wiring harness that controls the injectors.  Repair may entail wire repairs.

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