Dr. Gizmo Solves Your Car Troubles: Pt. 5 Page 3

January 14, 2010

1997 Ford Mustang

It is also possible that there is a fault in the security system but I think a fault is a remote possibility so focus on the wiring.  You likely will find the trouble in a harness.  Repair might be as simple as replacing a section of wire.

Instrument Cluster Goes Bonkers

Question 5

I love my 2001 Cadillac Seville, but during the winter months, the instrument cluster goes nuts.  Sometimes the dash works fine.  At other times the gas gauge may read full when the tank is near empty.  The temperature gauge may read cold when the engine is normal.  The outside temperature reading might say 20 below when it is above freezing.  Even the tire pressure might read 100 psi when the tires are at normal pressure.  Sometimes the lights wont turn on.  I just dont know what the instruments will read.

I spoke with my mechanic at my local garage about the trouble. He said he could not fix the trouble unless the dash is acting up when it is in his shop.

What do you think is wrong?  T.M., email

Answer 5

The most common problem with this type of dash is a failed instrument cluster but this is not always the case.  The instrument cluster communicates with several modules.  All of the modules obviously are connected to the cluster via wiring.  Therefore, it is possible there is a loose connection either at a ground or power wire.  There also can be a faulty module.


What your technician can do is test the system to determine if trouble codes indicate a problem within the instrument cluster or if it is somewhere else.  If tests conclude that the cluster is at fault, he can replace it with an exchange unit or send it to a facility for repair.

If there is a problem in a module or wiring, he needs to troubleshoot the wire harnesses and test the modules.  Repair depends on his findings.

Faulty Switch Flashes Warning 

Question 6

The Winter/Economy light is flashing in my 1997 Volvo 960 with 121,000 miles. The car starts and drives fine.  I do not feel any issues in the transmission at all except that the light is flashing.

I am concerned that something major is about to fail.  Whats up?  M.A., email

Answer 6

There is a safety switch on the transmission known as a PNP switch that might have a fault.

Try this.  When you are parked with your foot planted on the brake, move the transmission shift lever back and forth many times.  Doing so often cleans the contacts within the switch.  Turn off the engine and then start it up again.  If the light is not blinking, you have temporarily resolved your concerns.  However, more than likely the flashing light will soon return.  If so, it is time to take the vehicle to a repair shop to have the trouble diagnosed.  More than likely a technician will find that the switch has a fault and needs replacement.

Thanks for all of your great questions.  Dr. Gizmo cant 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@drgizmo.ws  01/05/2010 ® DR. GIZMO © 1989-2010

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