Coolant temperature sensor connector 2000 to 2002 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

martsink · 10-07-2015, 01:09 PM

Hey guys,
I'm trying to find out if the coolant temperature sensor changed from year 2000 to 2002?
I bought a 2002 harness for my 2000 Boxster S V8 swap and I can't get the water temperature gauge to work. From the diagrams, it seems like the wiring was switched from 4 to 2 wire connector? Is this correct? Did the sensor change as well? Can I still make it work somehow with two wires?

Thanks!

Does anyone know where I can get a connector pigtail?

BYprodriver · 10-07-2015, 01:58 PM

Yes to all your questions.

No I don't know how to make it work other than installing a Porsche approved engine.

martsink · 10-07-2015, 02:03 PM

Quote:

Originally Posted by BYprodriver

Yes to all your questions.

No I don't know how to make it work other than installing a Porsche approved engine.

Haha the Porsche approved engine is not longer an option! Thanks for the input, I guess I just have to get a connector pigtail somewhere.

BoxsterLS376 · 10-07-2015, 02:13 PM

The right sensor should only be about $20-$25.

martsink · 10-07-2015, 02:26 PM

Quote:

Originally Posted by BoxsterLS376

The right sensor should only be about $20-$25.

Hey John,
I think the issue is in the harness not the sensor (but im not sure tbh). The previous owner sold the harness and butchered some of the body wiring. Now I'm trying to piece it all together. Yours is a 2000 Boxster right? Mind checking what sensor you have and how many wires go to it? This is the sensor that I'm using, which has 2 pins, so I don't get how it can have 4 wires.

itsnotanova · 03-31-2016, 03:35 PM

Vlad, I just came across the same problem installing a 2001 3.4 into my 2000 3.2 S.
The 3.4 and a 1999 2.5 both have the 4 prong coolant temp sensor but every 3.2 harness I looked at has the two prong sensor. Not sure what the extra wires are for

martsink · 04-01-2016, 10:23 AM

Quote:

Originally Posted by itsnotanova

Vlad, I just came across the same problem installing a 2001 3.4 into my 2000 3.2 S.
The 3.4 and a 1999 2.5 both have the 4 prong coolant temp sensor but every 3.2 harness I looked at has the two prong sensor. Not sure what the extra wires are for

I think some 2000 3.2s got the 4 pin and some 2 pin sensors. The two extra wires are for the instrument cluster to display temperature

rennpart · 06-07-2023, 02:28 PM

Just ran across this old thread as it is the only info on the net.

Rebuilding a 2000 Boxster S of mine in my shop that had an engine fire and had the same issue.

If you use the 2 wire sensor on a 4 wire DME you will get a coolant reading via OBD2 but not on the dash.

The fix is as follows:
If your car (read DME) is an original "4 wire" car then you need to use the 4 wire sensor and run them to the trunk area.

If you splice the two wire sensor in your dash will not read correctly as the 4 wire sensor spits out different ohms to the ECU vs the instrument cluster.

Hope this helps someone in another 8 years!

--Aaron

martsink · 06-07-2023, 02:47 PM

Quote:

Originally Posted by rennpart

Just ran across this old thread as it is the only info on the net.

Rebuilding a 2000 Boxster S of mine in my shop that had an engine fire and had the same issue.

If you use the 2 wire sensor on a 4 wire DME you will get a coolant reading via OBD2 but not on the dash.

The fix is as follows:
Splice an additional wire off of PIN 22 blue/white wire at the DME and attach the other end of it to pin 29 on the black connector in the trunk (X3/1 connector IIRC it's the black connector in the bundle of 3 connectors on the LH side of the trunk).

Hope this helps someone in another 8 years!

--Aaron

Thanks Aaron, this is great info! I actually never got around to getting mine fixed, since I used a digital display and pull from the GM temp sensor (I have a LS swapped Boxster). Will give this a go!

rennpart · 06-08-2023, 07:58 AM

tt
--Aaron

Uwe · 06-16-2023, 11:37 AM

My temperature gauge stopped working, it simply wouldn't read any longer one morning. The red indicator seems to be working, it comes on with key on, goes out after start. The coolant level sensor system is working also.( slow blink with coolant level low) But the gauge reads nothing. It WAS working fine since the time I bought the car. The chassis is a 2000 Boxster S, the engine was replaced with a low mileage unit from a 2002 Boxster S previous to my ownership. The Coolant sensor inside the coolant jacket driver side engine front is a 4-prong unit, and so is the connector. I bought a coolant sensor specific to this car, but its a 2-prong sensor, so thats no good to me.
Has anyone had tihs experience, and if so, any tips on how to test the gauge itself would be much appreciated.

Starter986 · 06-16-2023, 12:25 PM

Quote:

Originally Posted by Uwe

My temperature gauge stopped working, it simply wouldn't read any longer one morning. The red indicator seems to be working, it comes on with key on, goes out after start. The coolant level sensor system is working also.( slow blink with coolant level low) But the gauge reads nothing. It WAS working fine since the time I bought the car. The chassis is a 2000 Boxster S, the engine was replaced with a low mileage unit from a 2002 Boxster S previous to my ownership. The Coolant sensor inside the coolant jacket driver side engine front is a 4-prong unit, and so is the connector. I bought a coolant sensor specific to this car, but its a 2-prong sensor, so thats no good to me.
Has anyone had tihs experience, and if so, any tips on how to test the gauge itself would be much appreciated.

Hey Joshua Tree. Yucca Valley here.

Have you checked fuse? Relay? Tried "tapping" on gauge shroud?

Uwe · 06-16-2023, 05:00 PM

Quote:

Originally Posted by Starter986

Hey Joshua Tree. Yucca Valley here.

Have you checked fuse? Relay? Tried "tapping" on gauge shroud?

Tapping, yes. Harder tapping, Yes. Connector on temp sensor wiggling, Yes. Fuse, no. I presume that the temp gauge won't have its own fuse, and everything else works fine except the cruise control, and it's fuse is good. What Relay are you referring to?

Yucca Valley here, too. I use JT because most people know where that is, as opposed to YV.

Starter986 · 06-17-2023, 06:29 AM

Quote:

Originally Posted by Uwe

Tapping, yes. Harder tapping, Yes. Connector on temp sensor wiggling, Yes. Fuse, no. I presume that the temp gauge won't have its own fuse, and everything else works fine except the cruise control, and it's fuse is good. What Relay are you referring to?

Yucca Valley here, too. I use JT because most people know where that is, as opposed to YV.

Relay? Likely no relay. Threw it out there because I didn't check to see if we had one or not. Likely just one fuse for all the gauges.

I use 92262 in my sig because people know where is Palm Springs.

We'll connect sooner or later.

rennpart · 06-19-2023, 07:40 PM

Just reporting my findings.

I edited my post.

If you "tap" a 2 wire sensor on an original 4 wire DME/instrument cluster car the instrument cluster temps won't display properly (reads very low)- the additional 2 wires on the 4 wire sensor output different ohms for the dash gauge.

I ended up having to use the 4 wire sensor and run 2 new wires. One is a ground, and the other has to go to the black XR2 connector in the trunk. I ran the ground to the trunk as well and tapped into the original ground source just to be safe.

--Aaron

Uwe · 06-28-2023, 05:33 PM

Replaced 4-prong coolant temp sensor. No result.
So I poked around in the trunk last night checking "stuff" out, I might have found the cause for my malfunctioning coolant temperature gauge. Indeed there are 2 wires running into the forward facing trunk cavity. A brown wire and a blue/red wire, just hanging there outside any of the wire looms in the vicinity. Light tugging produced 2 app. 24in long wires, both cleanly severed from their bros in the engine bay. I suspect rodent damage. The wires would have been severed at the rear end of the engine near the trans, judging by the length that was left.
Wish I had thought of not just verifying its 4 wires, but actually following them to their destination while I had everything unbuttoned last week to replace water pump and thermostat.
I'll be really good at doing the top and carpet tango very soon, I fear.
I am reasonably sure that the wires belong to my temp gauge, not the (possessed by Satan himself) rodent.

Dallas_986 · 07-08-2023, 07:26 AM

Quote:

Originally Posted by rennpart

Just reporting my findings.

I edited my post.

If you "tap" a 2 wire sensor on an original 4 wire DME/instrument cluster car the instrument cluster temps won't display properly (reads very low)- the additional 2 wires on the 4 wire sensor output different ohms for the dash gauge.

I ended up having to use the 4 wire sensor and run 2 new wires. One is a ground, and the other has to go to the black XR2 connector in the trunk. I ran the ground to the trunk as well and tapped into the original ground source just to be safe.

--Aaron

Aaron,

I’m working through this exact same issue on my car that I replaced the engine on. Could you provide some more detail on how you connected onto the 4 pin temp sensor, got the two “original” wires to the 2 pin connector on the engine harness, and where/how the two “added” wires connect into the XR2 connector?

I’m competent enough with nuts and bolts to do the engine swap but electrical stuff is outside of my knowledge base. Thanks!

Uwe · 07-10-2023, 10:23 AM

My issue was caused by a rodent, most likely. Found several pieces of blue/red wire and brown wire cleanly severed. No rotating components in the area of damage. ran a new 2-wire loom from temps sensor to trunk, connected there and voila! Gauge now works. This after replacing the 4-wire sensor and cleaning the connector with de-oxit.

redpepperracing · 07-10-2023, 12:02 PM

Quote:

Originally Posted by Uwe

My issue was caused by a rodent, most likely. Found several pieces of blue/red wire and brown wire cleanly severed. No rotating components in the area of damage. ran a new 2-wire loom from temps sensor to trunk, connected there and voila! Gauge now works. This after replacing the 4-wire sensor and cleaning the connector with de-oxit.

Nothing to add, other than to applaud the correct use and spelling of voila.

elgyqc · 08-06-2023, 10:42 AM

I just finished swapping a replacement engine into my 2000 S and on start-up saw that the temperature gauge was not reacting. This thread seems to have the answer to my problem, I just have to get all the steps straight.
The original engine had a 4 pin temperature sensor and 4 pin connector. The replacement engine (which came from a 2001 S) had a 2 pin sensor and connector.
So I need a 4 pin sensor (have that from the old engine)
A 4 pin connector (I'll have to source that), connect the 2 wires from the 2 pin connector and add 2 other wires from the 4 pin connector to the trunk where 1 goes to ground and the other "has to go to the black XR2 connector in the trunk".
Can someone clarify which pins are which (on the 4 pin connector)?