blinking coolant temperature LED

[DanHoug]

[Fhak915]

10-4
Thank, I got the yellow ones, not the aluminum one, not an electrical engineer so how do you tell the polarity?
The caps are in the mail, so I can’t tell if there is designations or what not.

Thanks so much.
_________________
Frank
86 AW EJ22

[DanHoug]

[Fhak915]

Hello vanagon experts,
Guess I am chasing this issue on my 86 vanagon with stock coolant tank a bit longer.
Some of the electrical lingo here is a bit over my head but I’m dangerous enough to try to follow along.
Had the constant blinking light and after changing the coolant to verify the mixture, grounding the sensors wires, pulling the relay at the fuse block, the led continues to flash or blink.
I thought this was my only hope but after opening the temp gauge, everything looks good.
I’ll swap out the capacitor but this one looks good.
Not sure I want to take it all apart again if this doesn’t work, so was considering cutting the led to keep it from flashing.

I wonder if anyone would have any advice.

I’ll try reading this tread again but I suspect I might not fully understand this system.

Love this forum, learned so much from a distance, figured I’d try to reach out.
Thanks,
Frank
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Frank
86 AW EJ22

[coastdog]

Followed the wire continuity from control relay through the connectors and the low coolant sensor and back to ground. I found the BL/G wire slightly backed out of the round 7 pin connector. System works as designed now. No flashing red LED. When I disconnect the plug connector on the top of the level sensor, the red light flashes after about 25 seconds. I have the GoWesty audible alarm installed and it sounds as well😃

Thanks for your help Mark!

Bill

[crazyvwvanman]

VW says that both conditions can cause it but I have doubts about the weak coolant end of it.

After working on the cooling systems on dozens of vans I have not experienced this. Some of those for sure had weak or mostly water for short test periods and didn't experience the flashing led in around town driving.
Maybe none of them had way too concentrated of coolant so I can't say if that would at some point be a problem.

When there is mostly water and more load driving I have experienced localized over heating which blows out some coolant and then gives a genuine low coolant warning.

Mark

[coastdog]

One more question as I dig into this problem today. I have read that the glycol to water ratio is critical for the coolant low level warning system to work properly and that 50/50 is the correct ratio for a number of reasons. The main reason being correct continuity//resistance between the sensor pins.

So can both a too concentrated and too dilute coolant ratio affect the function of the coolant low level warning system?

[coastdog]

Wow thanks for the quick response and information Mark. Is the signal wire tbe blue/green and does the brown ground from the other sender pin go back through the 7 pin connector before grounding under the coil.

I will check the signal wire as you described along that routing for a break or bad connection. Also try a new relay if I can find one.

[crazyvwvanman]

That indicates a possible failed 42 relay but more likely a problem in the engine compartment.
The signal wire to the 42 relay from the coolant tank level sensor has a connection in the engine compartment wiring box, in one of the round 7 pin connectors. From there it goes to the 2 pin wiring connector in the top of the level sensor in the top of the coolant tank. From there the other wiring pin is a ground wire from there over to the body near the ignition coil.

A break or bad connection anywhere along that wiring path will cause what you are seeing.
A common trouble spot is the 2 pins of the sensor connection.
These can get corroded badly at times and stop making a reliable connection.
I have had to replace the wiring connector in several vans to get a reliable connection.

Mark

[coastdog]

Are crazyvwvanman or dbreiel still monitoring this thread?

I have read all of this and still need some help.

My temp gauge light blinks correctly at start up and then blinks continuously again about 30 seconds after starting the engine or having the key in the run position. If I pull out the coolant level warning control module the blinking stops. The van is 1988 and the module is a 42.

[Nuthin2It]

Hopefully my solution to this problem is not already in this thread. I read through it all, with special attention to David Beierl's posts, but, I confess, I may have glazed over a few times.

I've been confounded by the red blinking light for a couple of years. It first appeared when we were in eastern Washington state (we live in Atlanta). The light blinked for a full day, then, thankfully, cured itself for the rest of the trip.

The light finally came on and stayed on a few weeks ago. Time to figure this out. When I pulled the Engine Coolant Level Relay, the light went off. Yes! Ordering a new one, though, was a problem. The guy at EuroCampers said the manufacturer discontinued them. They certainly seem to have disappeared from the vendors' shelves.

While waiting for another “order canceled” email, I checked the relay again. The light stayed on! Back to troubleshooting. Without going through all the things I tested and tried (this thread is already way too long), I discovered that the nuts on the posts behind the temperature gauge were loose. Holding a deep socket with my fingers, I snugged them down. Problem solved.

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1985 Westfalia 15 degree EA288 Boxeer

[SyncroHead]

I learned somethig new this week. Don't know if this has been written about before...

Crazyvanman has described the issue where if you have the issue with the coolant light blinking while the level is full and the coolant is, well, cool - then is may very well be a deteriorated component in the coolant gauge's blinking circuit.

What I learned is that upon starting a van that has this issue, if you turn the key to the ON position without starting and let it stay in this condition for a bit (I've done about 6-8 seconds) the blinking light will go OFF when you start craning the starter and stay OFF.

I've not done any research to determine why this happens, but I've now seen two vans where this is the case. So, for now at least, I'll just pretend my Syncro is a diesel and I'm waiting for the glow plugs to warm up.

Regards,
Jim Davis
_________________
"A Vanagon? It's not a car or a van. It's a hobby!"

Check out:
www.VANAVATION.com
www.SyncroSafari.org and
www.Vanagons.org

[Achilles3588]

[sagebus]

Really happy you solved that mystery Larry, good for you. Simple little things like this can be so frustrating for some folks like me.
_________________
1984 Vanagon GL, Wolfsburg Westy 1.9 ltr

[Achilles3588]

It was good to step away from this for a while. Head clearing exercise.

So started by checking the coolant level sensor ground - no problem there.

Then checked continuity of the power side - the blue green wire from the coolant level sensor to the junction box in the Vanagon engine bay. Aha! Found and repaired a break in the wire not 4" from the sensor.

Problem solved!
_________________
Larry V.~
'91 Syncro Doka 1.9L TDI 'AFN'

[Achilles3588]

[runningfix]

Ok, reading between the lines I’m assuming you’ve recently replaced the original PCB with a GW board and alarm following which all was working as it should except there was no movement from the temperature needle, hence the logical step to replace the engines temperature sender. Since then you get the LED self test as normal, but now the needle climbs steadily until (after circa 30 seconds from engine cold) it stops just at the overheat zone, the LED lights up and the alarm goes off (as they both should). Yes.

I would question if the new temperature sensor is faulty or if it’s the correct one for your engine. It’s not a grounding issue in my mind otherwise the needle would climb more quickly than 30secs and keep going past where yours stops. Have you put the old sender back in to see if it all returns to the original state with no LED and alarms (and no needle movement). Temperature senders are only a few dollars so I would be inclined to check if you have the correct or a faulty sender and order another before getting into the gauge internals.

[Achilles3588]

[runningfix]

Hmm, above my paygrade methinks. If it was me I would be thinking that 9.6v at the PCB temperature sensor terminal (yes) is lower than it should be from engine cold, but not so low as to peg the needle so high (others here can be exact on what 9.6v translates to in F/C deg coolant temperature). To me it suggests a gauge sensitivity issue or perhaps some erratic voltage behaviour (was it working correctly in the past). The coolant level side should have no impact on the needle, and with relay 42/43 removed you should still get the LED self test (do you). Since the LED and alarm go quiet with relay 42/43 removed, I would be looking at the coolant level side (have you tested the relay is working correctly) before moving onto the temperature needle side to figure out the why of the 9.6v.

A test lamp is meant to test between a negative and positive source – so an in-line test between two negative points shouldn’t generate a light, but might have a capability to test continuity with a short residue flash (?).

btw, I believe you should have relay 42 not 43 (or an older tall 43) in your year/model. What do you have?

[Achilles3588]