This gauge displays water/coolant temperature. If a problem is sensed by the warning system, the red light will flash.
The sender for this gauge is mounted in the upper radiator hose flange on the cylinder head.
1990+: The warning light is also tied into a level sensor mounted to the coolant reservoir.
The needle should be around or on the light under normal operating conditions. In stop-
What temperature corresponds to the needle reading?
Very good question! It all depends on what thermo switch is installed in your radiator and which thermostat is installed. The standard, OEM thermo switch is a 95-
If the needle pegs to the right and the light flashes at start-
If coolant gauge is reading low even after the engine is warmed up, it's indicating that the thermostat and/or the gauge sender is most likely faulty. Test the gauge sender (CIS -
First, test the gauge. If the coolant temperature gauge is not working properly along with the fuel gauge, and/or there are other elctrical issues with the instrument cluster, test the voltage stabilizer. For more voltage stabilizer information, see below.
If all of the preceding are found to be okay, the temperature gauge sending unit and/or level sensor ('90+) and/or the gauge itself could be faulty. Please refer to the cooling system and/or electrical page for further information.
There were two fuel gauge sending units used, both of which are now NLA (no longer available new). You will need to source a working used unit (please see the parts page for used parts sources. The sending unit can be accessed by removing the rear seat, followed by the round cover.
Part number (1984.5+): 533919051F
Fuel gauge doesn't work
Please click here for troubleshooting and testing the gauge.
The gauges are pre-
Turn Indicator Light
Flashing = turn indicator is on
Fault in the indicator circuit. First, check fuses #4 and #19 (1980-
This issue is mainly caused by a bad bulb. Check all turn signal bulbs and replace as need be.
Indicates a problem with the charging system.
This is normal. Current from the battery to the alternator is routed through the charging system warning light in the instrument cluster via a blue exciter wire. Once the alternator's output equals the battery's voltage, the warning light goes out, indicating that the alternator is now charging the battery (volt gauge jumps from 12 to 13-
Faulty alternator, faulty voltage regulator, loose/broken V-
Discharged battery, indicator bulb is burned out, no voltage due to faulty wiring/connectors. Please refer to your repair manual for further diagnostics/repair information.
Faulty alternator diodes and/or short in the wiring.
Oxygen Sensor (or EGR) Light
Indicates that it's time for an oxygen sensor replacement (every 30,000 miles); 1988+ Cabriolets do not have this warning light (sensor replacement interval is 60,000 miles). 1980 Cabriolets have EGR lights indicating it's time for an EGR valve replacement.
To turn the light off, carefully press the white (or red) button on the mileage counter box (black box located behind the coolant reservoir and attached to the firewall) all the way in using a pen or similar tool.
Note: This warning light is based solely on mileage; it is in no way connected to the oxygen sensor!
Oil Pressure Light
Indicates that engine oil pressure is too low & is usually accompanied by a buzzer.
More than likely, the problem lies with incorrect oil weight, incorrect oil filter type, oil sending unit is faulty, and/or oil sensor(s) is faulty. Click here for further information on the warning system and how to test it.
More than likely, the problem lies with a faulty oil pressure switch.
High Beam Light
Idicates high beam lights are on.
Manual transmission only, up to '87. For best fuel economy, shift to next higher gear when light comes on.
Upshift/reverse light switch faulty, vacuum switch faulty, no RPM signal from coil.
LED or cluster connection faulty, upshift/reverse light switch faulty, vacuum switch faulty, faulty wiring/connections, control unit (relay) faulty.
See the electrical page for component locations.
Airbag Warning Lights
Indicate that the airbag system needs servicing. When the lights are lit, the airbag system is inoperable. See the airbag page for further information.
Digifant I Cabriolets only.
When the check engine light is on it usually means that there is a fault in the emissions system. Performing an OBD I scan will a) tell you what the problem could be and b) clear the code(s) and turn the light out. The OBD I scan tool port is under the shift boot, towards the front (OBD II scan tools cannot be used to read OBD I codes unless they have an adapter). Click here for a list of fault codes.
Making the Cluster Lights Brighter
How to Set The Clock
Using a sharp pencil, ballpoint pen, toothpick or pin, press the black "buttons" on either side of the clock at the bottom of the instrument cluster to advance the minutes and hour.
Want to change the clock to 24-
If the coolant temperature gauge is not working properly along with the fuel gauge, and/or there are other elctrical issues with the instrument cluster, test the voltage stabilizer.
Manufacturer: ITT Semiconductor
Specs: 10V output, 220mA current limit
Output tolerance: ±2%
Max operating temp: 125°C
Storage temp: -
Pins: 1 (output), 2 (ground), 3 (input)
Direct replacement stabilizer:
Manufacturer: Fairchild (now ON) Semiconductor
Specs: 10V output, 250mA current limit
Output tolerance: ±2%
Operating temp: 0° to 125°C
Storage temp: -
Pins: 1 (input), 2 (ground), 3 (output)
The original TO202 stabilizer housing is obsolete; replacement housing is TO220. If your existing 10V stabilizer is faulty, replacements can be found through the following retailers:
North America: Mouser Electronics
UK/Europe: RS Components
Part #KA7810AETU (RS stock #806-
Part #LM7810CT (RS stock #806-
Part #KA7810ETU (RS stock #739-
Worldwide: Volkswagen dealers and eBay (VW part #171919803; these options come with the required metal spacer and longer screw; the eBay seller also includes an added heat-
Note: New voltage stabilizers are opposite from original (TO220 vs. TO202 housings, respectively); they will need to be flipped over, using a metal spacer and longer screw to install correctly.
The odometer gears are broken and/or out of alignment. Please see the DIY Guides sidebar for epair how-
The cable has most likely become detached from the instrument cluster. For those cars with oxygen sensor counter boxes, the box and/or its attachment points could be faulty. Another possibility is that the cable's drive gear in the transmission has become faulty, or has gone missing.
If the above two issues cannot be resolved, you may need to source a working used unit. Or, send your speedometer to a qualified repair shop such as Hollywood Speedometer or Palo Alto Speedometer, both in California.
It may simply need lubricating: Detach the cable from the instrument cluster and/or OXS counter box (attached to firewall, up to '87 models). Spray Tri-
Replace the main ground cables and clean all other ground points. If that does not help, remove the speedometer and make sure there is enough spring tension on the needle. If the tension is lacking, carefully remove the needle, wind the spring, and replace the needle.
The speedometer is broken and must be replaced. NOTE: Be sure to replace the battery ground cables first, making sure the contact points on the body and transmission are clean (1990+: also make sure that the Digifant ECU ground in the rain tray is clean and tight). If the car has poor grounds the electric current will seek a less-
Yes, the 2-
What about he OXS counter box? The box is nothing more than a mileage counter. When replacing the 2-
Speedometer Cable Part Numbers
The number below the MPH or km/h on the speedometer side of the instrument cluster is the calibration of the speedometer to its transmission gearing (or: the number of revolutions required by the speedometer cable divided by 100 to travel a distance of 1/100th of a mile, which is 52 feet, 9.5 inches). Cabriolets use 1540 speedometers, whether it's a VDO or Motometer instrument cluster. USA speedometers are calibrated for 1000 RPMs at 60 MPH, while European speedometers are calibrated for 1000 RPMs at 100 km/h. Cabriolets (and their Scirocco counterparts) use European-