Cayenne Low Coolant Sensor Bypass
Thread Starter
6th Gear
Joined: Dec 2020
Posts: 6
Likes: 0
Cayenne Low Coolant Sensor Bypass
Hello,
I've search the forum and can't seem to find the answer. I have a low coolant light on (2004 Cayenne S) but have confirmed that the coolant level is fine. I'd like to temporarily bypass the low coolant sensor.
I've unplugged the wire to the sensor, no luck, I also tried jumpering between the 2 wires on the plug. No luck.
Any ideas?
Regards
I've search the forum and can't seem to find the answer. I have a low coolant light on (2004 Cayenne S) but have confirmed that the coolant level is fine. I'd like to temporarily bypass the low coolant sensor.
I've unplugged the wire to the sensor, no luck, I also tried jumpering between the 2 wires on the plug. No luck.
Any ideas?
Regards
Thread Starter
6th Gear
Joined: Dec 2020
Posts: 6
Likes: 0
RL Community Team
Rennlist Member
Rennlist Member
Joined: Oct 2007
Posts: 28,647
Likes: 8,436
From: Clemson, SC
Can't you pull the stalk forward or use the up or down stalk toggles to clear the error and get the regular dash functions to display again. That should just leave the exclamation point illuminated but get the message off the screen.
Thread Starter
6th Gear
Joined: Dec 2020
Posts: 6
Likes: 0
Pulling the stock forward activates the windshield washer function. Pressing the toggles does nothing, it won't clear the screen when it's a message that is highlighted in Red.
That is the reason why I'm looking for a way to trick the system into thinking that the reservoir is full.
I would really appreciate it if someone could put an ohm meter on the sensor on a full bottle and let me know what it reads, I'm thinking perhaps the system needs to see some resistance.
If I knew what that resistance is, I could put a resistor across the plug temporarily.
That is the reason why I'm looking for a way to trick the system into thinking that the reservoir is full.
I would really appreciate it if someone could put an ohm meter on the sensor on a full bottle and let me know what it reads, I'm thinking perhaps the system needs to see some resistance.
If I knew what that resistance is, I could put a resistor across the plug temporarily.
Pro
Joined: Sep 2019
Posts: 533
Likes: 192
If You are anyway going to replace the coolant reservoir later, why not get a new one now and measure the resistance from that one. Or just replace the tank even if it's cold outside, it's like a 45 minute job.
If You are absolutely certain You want to use a resistor across the terminal, I can check the resistance later today.
If You are absolutely certain You want to use a resistor across the terminal, I can check the resistance later today.
Last edited by hopsis; Dec 8, 2020 at 03:13 AM.
Thread Starter
6th Gear
Joined: Dec 2020
Posts: 6
Likes: 0
I did purchase a new one from Fleabay - big mistake - It came damaged. When I shake it, I hear a rattling noise inside. It seems that the sensor is broken inside.
As far as the cold, I spent the last 20 years in the Caribbean and I really am not enjoying the winters in The Great White North.
It would be great if you could measure the resistance for me.
As far as the cold, I spent the last 20 years in the Caribbean and I really am not enjoying the winters in The Great White North.
It would be great if you could measure the resistance for me.
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Pro
Joined: Sep 2019
Posts: 533
Likes: 192
I went to measure the sensor resistance, my Fluke multimeter showed open between the terminals. Most likely that would change if the coolant level was under minimum level. Secondly, there most likely is a series and/or paraller resistors built in to the level sensor circuit so that the ecu can differentiate between open circuit, short to ground and low level faults. Or maybe the level sender is of type that requires voltage to work (like heated sensors on some BMW's), I didn't backprobe it with the engine running. I also didn't measure if there is any voltage coming to the sensor connector but that You can do yourself.
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Burning Brakes
Joined: Jun 2009
Posts: 1,212
Likes: 163
From: Bay Area, CA
I don't know how the sensor works on these cars, but I also have an X5, and do notice similarities in design between the two in general, so maybe what happens there is relevant.
Here's a thread on how that X5 sensor works, with lots of puzzlement and then the answer revealed in post #16 as to how it works.
https://xoutpost.com/bmw-sav-forums/...l-message.html
https://xoutpost.com/1111950-post16.html
In that design, a reed switch is used, with two magnets to trigger it. The sensor is in a dry well, so it is not exposed to the coolant. And it will rattle if shaken when dry, so maybe your eBay unit is not as bad as you think. So it's a switch, no resistance, just open or closed. An open circuit triggers the warning, shorting the two pins together bypasses the sensor, making the warning go away. Since that's what you did as your first step and it did not help, it seems the system is not exactly the same. Still, it may be interesting and might let you figure things out. If you read that thread, you'll see things appear to be very confusing due to the tricky design, but it all is simple and clear once you know the answer.
Sorry, I'm away from home right now, so can't check my Cayenne for you. Good luck.
Here's a thread on how that X5 sensor works, with lots of puzzlement and then the answer revealed in post #16 as to how it works.
https://xoutpost.com/bmw-sav-forums/...l-message.html
https://xoutpost.com/1111950-post16.html
In that design, a reed switch is used, with two magnets to trigger it. The sensor is in a dry well, so it is not exposed to the coolant. And it will rattle if shaken when dry, so maybe your eBay unit is not as bad as you think. So it's a switch, no resistance, just open or closed. An open circuit triggers the warning, shorting the two pins together bypasses the sensor, making the warning go away. Since that's what you did as your first step and it did not help, it seems the system is not exactly the same. Still, it may be interesting and might let you figure things out. If you read that thread, you'll see things appear to be very confusing due to the tricky design, but it all is simple and clear once you know the answer.
Sorry, I'm away from home right now, so can't check my Cayenne for you. Good luck.