Date: Sun, 31 May 1998 17:00:37 -0400
Reply-To: averill@LDL.NET
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: George Averill <averill@LDL.NET>
Subject: Blinking Light in 84 Camper (Continued)
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I plan to do an exploatory operation on my 84 van in a few days to get to
the bottom of the blinking red light. Before I do this I need some ideas
from all of you technically minded fellows.
Question: Exactly what conditions will cause the red light to blink? What
sensors are involved?
The owners manual (pp.28-29) says, "The needle in the water temperature
gauge will indicate the temperature of the coolant shortly after the
ignition is switched on.
Engine operating temperature will vary with climate, traffic conditions and
engine load. Maintain moderate speed until the engine has warmed up.
When the engine is working hard and in stop-and-go-traffic, the needle can
show a very high temperature, but this is not serious as long as the
warning light does not flash.
For a bulb check the red light in the water temperature gauge will flash
for about 3 seconds when the ignition is turned on.
If the light flashes while driving, the engine may be overheated because of
low coolant level or V-belt damage. Move the vehicle a safe distance off
the road, stop the engine and depress the emergency flasher switch.
The fan should be operating when the warning light is on (listen for fan,
located in front of car behind grille).
If a visual check shows that coolant level and V-belt are normal, but the
warning light continues to flash, contact your nearest dealer to have the
cause located and corrected."
On page 63, the manual says, under checking coolant level, "...The
expansion tank is equipped with an electric doolant level checking device.
When the coolant level is too low, the warning light in the water
temperatue gauge (see page 30) will flash until the coolant level has been
restored to normal."
Now, from reading this and other information, I assume the following:
1. Low water level in the expansion tank will cause the light to blink.
(detected by the two sensors sticking in the tank. The resistance between
them goes up when they are out of the water.)
2. The wrong percent of antifreeze/water solution will cause the light to
blink. (This came from a tech. bulletin in the archives.)(This also changes
the resistance between the two sensors sticking in the tank.)
3. When the water is low, and the light starts to blink, whatever causes
the light to blink also turns on the fan. (I'm not sure about this one.)
4. Temperature over a certain degree? (I'm not sure if this is true.) Does
the water temperature sensor located on the engine trigger this? Does the
temp. sensor on the engine for the computer trigger this? Does the
temperature swich on the radiator trigger this? Maybe temperature doesn't
trigger it at all, just low water level. Maybe they all trigger the red
light to come on. Maybe the computer triggers it to come on. Does anyone
know for certain?
3. When the high fan speed comes on? (not sure about this either). I know
that when the air conditioner is turned on, the fan automatically comes on.
I'm not sure if it comes on in high speed mode or low speed mode. Does
anyone know? Is it normal for the fan to be turned on whenever the AC is
turned on, or has someone besides VW wired the camper this way? I have a
camper with the AC blower in the back rather than in the grill.
The problem would be simple to solve if the Bentley had a schematic diagram
of the electronic circuits that control the light rather than just a wiring
diagram. Does anyone have a copy of the electronic circuit that is used?
We can solve this problem for all times if everyone will work together on
this one.
George