Serving the Gainesville and Hawthorne Florida Area
Auto, Car, Truck Gages
What about a CHECK ENGINE LIGHT? How important is that?
A general rule of thumb: RED LIGHT: STOP!.... YELLOW LIGHT: CAUTION!
A red light means something bad has happened. Stop as soon as possible. If you ignore a red light and keep driving you may cost yourself a lot of money, or even kill yourself!
A yellow light is less urgent. The better your car runs, the less urgent the light is. For example, if your check engine light goes on when you are on vacation, and the vehicle still runs well and gets acceptable fuel mileage then you can probably finish your vacation and take it in to your regular mechanic for repair when you get back in town. A red oil pressure light on the other hand is cause to stop as soon as safely possible! A red "brake" light can be from 3 things: parking brake left on, low brake fluid, or off center proportioning valve caused by loss of pressure in the brake system. Once again if your brake pedal is firm you might be OK, but check the fluid level and operate your parking brake a couple of times to see if the light goes off. An amber "ABS" (Antilock Brake System) light warns of a problem that won't affect you under normal conditions, but if you start skidding on a slick road your antilock brake system may not work properly. Ditto with an amber air bag light: it's no problem as long as you're not involved in an accident!
The alternator light (or ammeter or voltmeter if a gage) isn't as crucial as the oil pressure and temperature light, but a charging system problem can leave you on the side of the road just like an empty gas tank can. Thus nearly every vehicle ever made has had an oil pressure, temperature, and charging system light or gage, and a fuel gage. Modern cars have a light or gage for so many functions that they look like a pinball machine when you first start them up! Even so, the "vital" ones are the temperature gage or light and oil pressure gage or light.
The advantage of the "Idiot light" is obvious: it is hard to keep track of a lot of little white gage needles on the dash while driving. People who don't know anything about cars can be confused by gages or will ignore them.
But ANY IDIOT will notice a bright red light on the dashboard!
Personally I like systems that have gages combined with a single "CHECK GAGES" red warning light. I have also seen gages that have a red warning light on the face of the gage. This gives you the best of both worlds.
Direct gages have the edge on accuracy and reaction speed, but they are a pain to install. the oil gages they sell today come with a tiny plastic tube which you connect to your engine oil pressure journals somewhere. Trouble is, this little tube has to thread its way past hot exhaust parts and a lot of sharp sheet metal on its way under the dash. One little slip against that hot exhaust, or a one cut from sharp metal under the hood or dash, and it can leak all the oil out in seconds! (If it gets cut under the dash, it can cover your feet in oil too! You'll be walking with hot oil in your shoes!) The temperature gages have a somewhat fragile copper line usually wrapped with a steel coil with a thermal bulb on one end. once again routing can be difficult. if you break the copper line from the engine to the gage you have to replace everything: the whole gage assembly.
A light sending unit provides its wire with either an open circuit or a closed circuit to ground: it's just a switch. The gage sending unit feeds a varying resistance to ground back to its gage.
in any case, most all sensors operate by providing circuit to ground, either a variable resistance circuit or an "on/off" circuit to ground.
One exception is an electronic speedometer sensor, usually called the vehicle speed sensor.. It has a magnet inside a wire coil and is usually linked by a gear to the output shaft of the transmission or transaxle. As the magnet spins faster, more current is produced in the wire coil. This current goes to the speedometer, where an electronic circuit moves the needle. On some vehicles this sensor provides data for the engine control computer , transmission control computer , and electronic cruise control. A digital speedometer uses the same sensor, but a computer takes the electric signal from the speed sensor, converts it to digital, and displays it on the dash.
Since most gages and operate by grounding the gage or light usually a test and repair is easy, needing no special tools. Disconnect the wire from the sensor or sending unit. Have an assistant BRIEFLY touch the disconnected wire to a good ground. A bent paper clip works well for "probing" an insulated terminal.
If it is a gage, it should "peg", or go all the way to one side or the other. If it is a light, it should turn on when grounded.
If the gage or light responds in this way, then your gage or light problem is probably from a bad sensor or sending unit. Repair as needed.
Click here for some images of car gages
A
ABS: Anti-Lock Brake Systems
ADVANCE: Car ignition timing
ALTERNATORS and Car Battery
AUTOMATIC TRANSMISSIONS
B
BAD CAR DESIGNS
Bad Drivers: How NOT to drive
BATTERIES: Auto, Car or Truck
BELTS AND HOSES
BEARINGS
BODY AND BUMPER REPAIRS
BRAKE REPAIRS: Car or Truck
C
Car Washing and Care
CARBURETORS:Car & Truck
CHECK ENGINE LIGHT
CLEANING: Engine Cleaning
CLUTCH REPAIRS: Car & Truck
COIL (IGNITION)
COMPRESSION: Car Engine
COMPUTER CAR CONTROLS
CV JOINT OR CV AXLES
D
DISTRIBUTORS (IGNITION)
E
ELECTRIC WIRING REPAIR
ENGINES: Car & Truck
ENGINE CLEANING
EXPANSION PLUGS
F
FILTERS: OIL, AIR, ETC.
FREEZE PLUGS
FUEL AIR MIXTURE
FUEL INJECTION: Car & Truck
FUEL PUMPS: Car & Truck
G
GAGES AND "IDIOT LIGHTS"
GASKETS AND SEALS
GLASS: WINDOWS AND WINDSHIELDS
H
HEADS & HEAD GASKET
HOSES AND BELTS
I
"IDIOT LIGHTS" AND GAGES
IGNITION COIL
IGNITION TIMING: Car & Truck
J
AUTO JACKS: lifting cars safely
K
L
LEAN "Car runs lean"
LIGHTS: WARNING OR "IDIOT LIGHTS"
Limp Home Mode
M
MIL Light
MANUAL TRANSMISSIONS
N
NO START: Car Won't Start
O
OIL CHANGES
OIL: What's right for your car?
OIL LIGHT ON OR GAGE LOW
P
PCV Valve
Q
R
RADIATORS: Car and Truck
RICH: Car runs rich
S
SEALS AND GASKETS
SERVICE ENGINE SOON LIGHT
SPARK PLUGS
STARTERS: Auto, Truck
T
THERMOSTATS
TIMING: IGNITION TIMING
TIMING BELT & TIMING CHAIN
TIRE REPAIR
TRANSMISSIONS: AUTOMATIC
TRANSMISSIONS: MANUAL
U
V
VACUUM ADVANCE
WARNING LIGHTS OR "IDIOT LIGHTS"
Car Washing and Care
W
WATER PUMP REPAIR
WINDOWS AND WINDSHIELDS
WIRING REPAIR
X
Y
Z
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