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IdahoDoug
Samba Member
Joined: June 12, 2010
Posts: 10251
Location: N. Idaho
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 Posted: Tue Mar 17, 2015 10:39 am Post subject: Installed new coolant tank sensor - light still flashing? |
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So, my temp gauge red light has been flashing since I got this girl. I'm always checking things and my coolant is always full and correct coolant ratio since I live in the north, so it never bothered me. Now with summer coming my wife may drive it once in a while so its time to fix it. I put a new coolant temp sensor in and it did not change. There are two wires, so I figured there is no wrong way to connect the wires - it's just a resistance value, right? That's my question. Thanks.
If you guys confirm this is true (no way to connect it backward), then I will be looking for help on identifying my coolant relay which is supposed to be atop the fuse box, I think? Help on that would be appreciated as well.
DougM
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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BlueGrasser
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Joined: August 27, 2014
Posts: 562
Location: Sacramento
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| Posted: Tue Mar 17, 2015 10:54 am Post subject: |
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Mine only blinked when my coolant level got a little low (small leak that I fixed). Are you sure it's not the coolant level sensor that needs replacing?
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IdahoDoug
Samba Member
Joined: June 12, 2010
Posts: 10251
Location: N. Idaho
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| Posted: Tue Mar 17, 2015 10:58 am Post subject: |
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Heh, may I suggest reading the post? I replaced the coolant level sensor and that is the subject of my post.
Also, I jumped back on here to add that the water guage has always read low and that has continued. The guage reads a couple needle widths from the bottom and sometimes sits at the bottom even though I'm whizzing down the freeway.
The coolant sensor was replaced a couple thousand miles ago and has not changed anything. There are no bubbles, etc. Pressure tank is always brimming full.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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BlueGrasser
Samba Member
Joined: August 27, 2014
Posts: 562
Location: Sacramento
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| Posted: Tue Mar 17, 2015 11:05 am Post subject: |
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I read it, but it was unclear whether you meant the coolant temp sensor (which you called out in the post), or the level sensor (which the title seemed to suggest).
I'm not trying to be a jerk or anything. Sometimes it is the obvious answer that alludes us. Not the case here so I will back out and let the experts weigh in.
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Going to where the grass is bluer...
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djkeev
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Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
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MarkWard
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Joined: February 09, 2005
Posts: 17155
Location: Retired South Florida
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| Posted: Tue Mar 17, 2015 11:12 am Post subject: |
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A paper clip across the coolant "level" sensor wire should disable that feature. My guess is since you replaced the sensor already, that with the harness jumped the light will still flash. I recall reading there is also a controller for that after a certain year. I also remember a thread about a coolant mix causing the problems with the level sensor. That seemed like a stretch.
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djkeev
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Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
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kamzcab86
Samba Moderator
Joined: July 26, 2008
Posts: 7925
Location: Arizona
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| Posted: Tue Mar 17, 2015 11:40 am Post subject: Re: Installed new coolant tank sensor - light still flashing |
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| IdahoDoug wrote: |
| There are two wires, so I figured there is no wrong way to connect the wires |
Correct.
However, these sensors can be bad out of the box. I bought a new level sensor purely for preventative maintenance a few years ago when replacing the coolant tank... light flashed immediately; sensor was bad, confirmed with a resistance reading with it sitting in coolant. Thus, put the original back in until it started leaking (O-ring was shot) and the new coolant tank went bust. Tried a local vendor for the sensor, checked the resistance, and it was on par with the original (had it not been, I simply would've swapped out the old O-ring); installed it and it's been working fine. The same problem occurs with the temp sensors and gauge senders too... it's a gamble getting good electrical components these days. 
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1986 Cabriolet: www.Cabby-Info.com
 1990 Vanagon Westfalia: Old Blue's Blog
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"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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Ahwahnee
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Joined: June 05, 2010
Posts: 9810
Location: Mt Lemmon, AZ
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| Posted: Tue Mar 17, 2015 1:55 pm Post subject: |
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| IdahoDoug wrote: |
| Heh, may I suggest reading the post? |
Oops.
A break in the wire may also get you a constantly flashing light. Happened to me in my 84 - break was in the harness somewhere below the coil. Easy to fix but took a while to find it.
There is a thread on the Samba to easily test the gauge using a few resistors -- that should narrow down the issue of your gauge reading low (which could also be a faulty or incorrect thermostat). |
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IdahoDoug
Samba Member
Joined: June 12, 2010
Posts: 10251
Location: N. Idaho
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| Posted: Tue Mar 17, 2015 8:16 pm Post subject: |
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BlueGrasser,
Please accept my apology! I wasn't upset - just chiding you - but I just got back on and realized MY mistake. Aagh! Indeed meant coolant level sensor.
Thanks for the info that the sensor is not polarized - any direction will work. I will check the sensor resistance to see if it is a problem, and then carry on with other checks.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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BlueGrasser
Samba Member
Joined: August 27, 2014
Posts: 562
Location: Sacramento
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| Posted: Tue Mar 17, 2015 10:59 pm Post subject: |
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| IdahoDoug wrote: |
BlueGrasser,
Please accept my apology! I wasn't upset - just chiding you - but I just got back on and realized MY mistake. Aagh! Indeed meant coolant level sensor.
Thanks for the info that the sensor is not polarized - any direction will work. I will check the sensor resistance to see if it is a problem, and then carry on with other checks. |
No worries. Hope you get it worked out soon!
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Tom Powell
Samba Member
Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Wed Mar 18, 2015 3:42 am Post subject: Re: Installed new coolant tank sensor - light still flashing |
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| kamzcab86 wrote: |
| IdahoDoug wrote: |
| There are two wires, so I figured there is no wrong way to connect the wires |
Correct.
However, these sensors can be bad out of the box. ... it's a gamble getting good electrical components these days. |
The OG sensor can be cleaned with vinegar. Often the terminal contacts are corroded and do not make the circuit. They can be exercised and/or cleaned.
Aloha
tp |
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IdahoDoug
Samba Member
Joined: June 12, 2010
Posts: 10251
Location: N. Idaho
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| Posted: Wed Mar 18, 2015 7:54 am Post subject: |
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Interesting line of thought that it could be bad right out of the box. I wondered that but it's hard to accept, if true.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader |
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Tom Powell
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Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Wed Mar 18, 2015 8:01 am Post subject: |
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| IdahoDoug wrote: |
| Interesting line of thought that it could be bad right out of the box. I wondered that but it's hard to accept, if true. |
A local mechainic says the dealership ones are best. I bought one at a local FLAPS. Am order, PM pickup, cleaned the OG sensor with vinegar, new one still in the box.
Aloha
tp |
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crazyvwvanman
Samba Member
Joined: January 28, 2008
Posts: 9937
Location: Orbiting San Diego
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| Posted: Wed Mar 18, 2015 8:21 am Post subject: Re: Installed new coolant tank sensor - light still flashing |
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In the fuse/relay panel position #3 should be a "relay" with the number 43 or 42 stamped on the visible end. PULL that relay. Then check to see if the constant flashing problem is still happening. If it is still happening with that relay pulled then it CAN'T have anything to do with the tank sensor or sensor wires.
Don't guess which part is bad and replace it, TEST and see if that part could even be the cause or not. Don't use the standard Samba gang method of "guess and replace".
Mark
| IdahoDoug wrote: |
So, my temp gauge red light has been flashing since I got this girl. I'm always checking things and my coolant is always full and correct coolant ratio since I live in the north, so it never bothered me. Now with summer coming my wife may drive it once in a while so its time to fix it. I put a new coolant temp sensor in and it did not change.....
I will be looking for help on identifying my coolant relay ..... |
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Snort
Samba Member
Joined: April 02, 2005
Posts: 1957
Location: Seattle, WA
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| Posted: Wed Mar 18, 2015 8:29 am Post subject: |
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When trying to figure out what is happening with your coolant gauge and blinking light it's best to understand how the entire system works. Here is the best explanation I have read on the subject. Your level indicator function is discussed at the end. Note that there is also an early and late version of this system that operates somewhat differently which pegs the needle of the temp gauge and it also uses a different relay.
| crazyvwvanman wrote: |
The electronics of the circuit board inside the temp gauge will react to an extremely short duration anomaly in the voltage that you couldn't see with a meter. I don't feel like going into a super detailed explaination of the circuit board right now but here is some. When you turn on the key 12 volt power is sent to the cluster, is stepped down to 10 volts by the voltage stabilizer, and then fed to the temp gauge module. The temp gauge internal circuit board has a capacitor on it. The capacitor takes time to fill up to capacity. Before it is full the led blinks. When it gets filled, the blinking stops. There is a current limiting resistor in the power feed to the capacitor. This resistor makes the capacitor fill up slower than it would without the limiting resistor. While the capacitor is filling the led blinks. The temp sender works by providing a leak for the power in the temp gauge to go to ground. The hotter the temp sender the faster the leak. (that is also what the gauge needle shows, the current flowing through the sender to ground, the temp gauge is a current meter) When the engine is too hot the temp sender drains the capacitor faster than the resistor will allow it to fill. That makes the led blink again when the engine is too hot. While the capacitor can drain in an instant it fills back up slowly because the limiting resistor restricts the fill rate. The led blinks until the capacitor it is full again. So just a tiny blip in the power feed can cause multiple blinks while the capacitor fills back up through the limiting resistor.
When the engine is cold the temp sender does not drain as much current from the gauge capacitor. So it takes more of a voltage anomaly to cause the false blinking when the engine is cold. Once the engine is warmed up there is always more current flowing from the gauge to the temp sender. That higher constant drain when engine is up to temp means a smaller interruption in the filling of the capacitor will cause the blinking with a warm engine than a cold engine.
(as a reminder, this blinking function has nothing directly to do with the coolant tank level sensor. That sensor goes to a relay and the relay connects to the gauge. The relay then provides an additional drain of the capacitor whenever the level sensor triggers the relay to do so. If you pull the coolant relay you remove the coolant level sensor system from any involvement in the gauge led behavior. This is a useful test to determine where the a false blinking is coming from. In this case this test has already been done and showed that the blinking was not from the coolant level warning system)
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kamzcab86
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Joined: July 26, 2008
Posts: 7925
Location: Arizona
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| Posted: Wed Mar 18, 2015 11:57 am Post subject: |
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| Tom Powell wrote: |
| The OG sensor can be cleaned with vinegar. Often the terminal contacts are corroded and do not make the circuit. They can be exercised and/or cleaned. |
Yes, but these sensors can go bad by other means than just corrosion. I've got my original under the rear seat in case the new one croaks out on the road.
| IdahoDoug wrote: |
| Interesting line of thought that it could be bad right out of the box. I wondered that but it's hard to accept, if true. |
Oddly enough, I bought a new temp gauge sender for my Cabriolet (no level sensor, thank god) as, again, preventative maintenance years ago while the system was drained... turned the key, gauge pegged and light flashed. Bad out of the box (and we're talking about a simple nail-head sender), so put the 20-year-old original back in. As already stated, my van's first new level sensor was bad out of the box (verified with a DVOM). It does indeed happen. So, time to do some testing to confirm which component in your system is faulty.
_________________
~Kamz
1986 Cabriolet: www.Cabby-Info.com
1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32632
Location: Reading Pennsylvania
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| Posted: Wed Mar 18, 2015 12:14 pm Post subject: |
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| kamzcab86 wrote: |
| Tom Powell wrote: |
| The OG sensor can be cleaned with vinegar. Often the terminal contacts are corroded and do not make the circuit. They can be exercised and/or cleaned. |
Yes, but these sensors can go bad by other means than just corrosion. I've got my original under the rear seat in case the new one croaks out on the road.
| IdahoDoug wrote: |
| Interesting line of thought that it could be bad right out of the box. I wondered that but it's hard to accept, if true. |
Oddly enough, I bought a new temp gauge sender for my Cabriolet (no level sensor, thank god) as, again, preventative maintenance years ago while the system was drained... turned the key, gauge pegged and light flashed. Bad out of the box (and we're talking about a simple nail-head sender), so put the 20-year-old original back in. As already stated, my van's first new level sensor was bad out of the box (verified with a DVOM). It does indeed happen. So, time to do some testing to confirm which component in your system is faulty. |
And I'll insert a shameless plug for VanCafe here.
A year or so ago I Ordered a temperature sending unit for the 2.1....... He called me and explained that while they ARE available he is NOT selling them due to severe quality issues with their operation.
First class outfit right there! Tells me that I can ALWAYS purchase with the confidence of getting known quality from them.
And a Cookie...........
Dave
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