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Mon May 19, 2014 9:00 am

leaving from cape cod to baja today light on temp guage is flashing.its not running hot ,coolant is full?? any ideas

Mon May 19, 2014 9:03 am

Check the expansion tank not the overflow tank for low coolant.

If you did then check the wires coming from the sending unit on the expansion tank.

The expansion tank has the "Black" or "Blue" cap with a hose attached.

Mon May 19, 2014 9:05 am

Is coolant full in the bottle with the pressure cap (not the one you see from the license plate)? If so then you likely have a bad coolant level sensor, a bad connection at the plug, or a bad wire. You can unscrew the level sensor and try cleaning up the probes. That sometimes does the trick.

(Edit: Syncro Jael types faster than I do. :D )

Mon May 19, 2014 9:24 am

thank you i talked to a local rescue squad guy and he says the same to check the coolant senser.gonna do that now

Mon May 19, 2014 9:36 am

I had exact same condition, tried all the above suggestions but nothing fixed the problem. I discovered that there is a time delay printed circuit behind the fuel gage. I replaced that and trouble is gone. You can also try letting the blinking light stop before starting engine

Mon May 19, 2014 11:25 am

found relay on use block with corroded terminals all set with that now the starters giving symptoms of going

Tue May 20, 2014 8:40 am

Chris (This is John - the Rescue Squad person you contacted.)

Hope is all is well now. For the those following along at home, when I was trying to find the resistance readings for the coolant sensor (man I need a Bentley at work), I found good info on BTDT.....and it was John Meeks himself (RIP) who had posted that article that led us to the relay.

So there you have the article, and the RescueSquad he founded, saved the day. RIP Mr, Meeks, you're still having a positive impact.

Tue May 20, 2014 8:53 am

there was also a tech bulletin on this back in 1992 from VW

found on http://www.vanagonparts.com/tech_bulletins.html#012

Quote: Technical Bulletin
Group: 90
Number: 92-03
Date: February 29, 1992
Subject: Coolant Indicator LED is Flashing at Normal Temperatures
Model(s): All Models

CONDITION
Coolant overheat / low coolant level indicator LED is flashing at
normal coolant temperatures.
SERVICE
Check the coolant indicator LED according to the list below.
The following applies IN ADDITION to tests listed in the Service
Microfiche. .

* refer to appropriate wiring diagram
* disconnect coolant level sensor electrical connector
* check coolant level in coolant reservoir
*** MUST be between MIN and MAX marks
* set digital multimeter, Fluke 83 (US 1119) to ohms function
* check resistance of level sensor with digital multimeter Fluke 83
(US 1119)
*** must be between 31K Ohm and 65K Ohm with correct COOLANT LEVEL
AND COOLANT CONCENTRATION.

NOTE
If coolant resistance is NOT within the above specifications, the
coolant MUST be drained and replaced with NEW coolant mixture of
50 percent water and 50 percent phosphate free coolant antifreeze,
Part No. ZVW 237 104. (In Canada, use Part No. G 001 100). The
mixing should be performed before filling vehicle cooling system.

*****************************************************************
* CAUTION *
* Coolant concentrations of 60 percent or higher will cause the *
* overtemp / low coolant LED to activate. *
****************************************************************

*****************************************************************
* CAUTION *
* Coolant antifreeze MUST NOT be reused. Properly dispose of *
* used coolant. *
****************************************************************

* reconnect sensor connector
* check coolant level control unit using wiring diagram

NOTE
The control unit is located on top of the fuse/relay panel on vehicles
up to 1989 model year and thereafter it is integrated into the multi-
processor of the instrument cluster circuit board.

* if wiring, coolant level sensor and coolant concentration are OK,
replace coolant level control unit or instrument cluster circuit
board
* refer to appropriate Service Microfiche Group 90 - Coolant
Temperature Gauge, checking and troubleshooting
* confirm proper operation of temperature gauge and blinking LED per
Service Microfiche Group 90

*****************************************************************
* CAUTION *
* Part Numbers are for reference only. Always check with your *
* Parts Department for latest parts information. *
****************************************************************

Technical Information
Group: 90
Number: 87-03
Date: July 31, 1987
Subject: Coolant Temperature Gauge Light flashes
intermittently / continuously
Model(s): All Models, all Model Years

Flashing coolant temperature light may be caused by:
- Low coolant level.
- Coolant level indicator.
- Electrical connections on gauge.

* Check coolant level, top up if necessary.
* Check coolant level sensor for continuity.
* Check for loose connection of wiring at terminal 14 connectors of
instrument cluster, nuts of temperature gauge, ground connection
to body and engine ground. Repair if necessary.

If temperature gauge light still flashes:
* Replace low coolant level control unit

Tue May 20, 2014 10:52 am

Thanks Dan - good info

FYI - here's the link to info from Jonh Meeks / BTDT

http://www.vanagonauts.com/printable.phtml?&catid=241

Mon May 26, 2014 7:40 am

i am having this problem but it is because the boot on the original connector doesn't fit the sensor quite right. i am told these new sensors are actually made for jettas or something and i would like to splice in a new connector but i just need to know what junkyard vw i need to cut it out of. any ideas?

Tue May 27, 2014 1:01 pm

If it's not any of the other problems listed above it could be a bad capacitor in the dash. When I bought mine I had the red light blinking constantly and the capacitor ended up being the culprit.

http://www.thesamba.com/vw/forum/viewtopic.php?t=353678

Sun Jan 01, 2017 4:15 pm

My flashing red coolant light went away over the summer but recently came back now that temperatures are colder (I'm in NJ). I took out the sensor and tested with an Ohm meter. I'm getting resistance results within the acceptable range of 31K Ohm and 65K Ohm at room temperature water. When I use coolant (Peak LongLife 50/50) stored at outside air temperature (now about 45 degrees), the reading is well over 200k Ohms. When I heat the coolant using my stove, it falls back within range.

This testing is consistent with what I get while driving. The light will flash until the van warms up. On restart, the flashing goes away.

I found a replacement sensor online for $10 so I'll try that and post my results.

Thanks for any information that may be helpful.

Happy New Year!

Sun Jan 01, 2017 4:32 pm

It is a crude approach but it seems like getting the tips closer together might resolve your issue (if all that is going on is higher resistance in cold coolant).

Possibly bending or simply soldering on an extension at a right angle might do it.

Since it is a make-or-break connection (not quantitative) then the function is served so long as coolant conducts and air does not.

Mon Jan 02, 2017 8:45 am

Thanks Ahwahnee. I took your advice and bent the prongs inward towards each other. As you suspected, the tests showed less resistance but still much more than spec. Curiously, the tests in the antifreeze were not very stable. Resistance fluctuated wildly, but always over 100k Ohms. With water, always somewhere near 40k Ohms. The testing antifreeze had also warmed up overnight indoors.

I put the sensor back in the expansion tank for now and noticed that the antifreeze in there was considerably darker than the new antifreeze I used for tests. I'm guessing that cold, used antifreeze offers more resistance than new antifreeze.

We'll see what happens when I put a new sensor in. In the meantime, I'm curious about whether or not the bulk of these coolant sensor-related issues happen in colder whether areas. I'm also curious to know if one type of antifreeze might prevent false triggers, or if it has more to do with temperature than coolant.

So, that's where I am now. Thanks for the assist.

Al

Thu Jan 12, 2017 5:55 pm

Update here: http://www.thesamba.com/vw/forum/viewtopic.php?p=8319418#8319418

Bottom line: replacing the sensor seemed to do the trick. Will post follow-up if that changes.

Thu Feb 02, 2017 7:19 pm

Could anyone opine if all the info here also applies to a 1.8T ? My temps are all fine. Scan gauge confirms but that blinking light is constant today. Haven't popped the engine cover to inspect how the coolant system may differ from stock. Maybe it's the same? Anyone happen to have this issue on a 1.8T? Obviously I need to start with a level check. Thanks

Wed Dec 20, 2017 12:44 pm

I tested the circuit for the coolant light on two vans. Both would read over the range mentioned here. One flashes, one doesnt. New control relay and new sensor. Still the same. Finally I swapped out the clusters and ureka!
Turns out there is a capacitor that goes bad.

http://www.vanagonauts.com/printable.phtml?&catid=241