94 Q45 Knock Sensor Harness / Coolent Temp Sensor Compatibility Issue

[off2sobe]

Are the temp sensors for TCS/non-TCS engines compatible?

I was sent (and installed) a base Q KS harness and found (too late) that the KS harness is different for cars with TCS than cars without.

I would like to just change out the temp sensor or splice in the old sensor plug to the new KS harness. I really don't want to pull the plenum again if I don't have to.

[DAEDALUS]

I don't see why they wouldn't be identical. Are the part numbers different? You can try asking Joe at 1-888-216-5328.

[off2sobe]

They are different part #.

LESSON LEARNED: MAKE SURE THE PARTS TECH CROSS REFERENCES PER VIN!!!

I need to know if the temp sensors are identical, just with different connectors (which wouldn't make a lot of sense). My other option is to splice the old plug to the new harness--I would like a definitive answer if this would be compatible.

[DAEDALUS]

2 reasons for being different: fit or function. I assume the function is the same for all parts, and for the temp sensors you can verify that the FSM only gives one resistance value range per temperature regardless of the vehicle's trim. I still can't see any reason for even having 2 part numbers, unless they were physically different sizes for clearance issues or something. Sorry I can't give you a definitive answer, but my choice would be to go ahead and splice/use what you have, and remove the plenum only if there are any problems, either during installation or when you fire it up. The knock sensor won't light the CEL but they will store a code if they're not working right.

[off2sobe]

I've rigged a temp splice (have not cut the new harness). I have a few more things to finish up, but should have her running tonight.

My hands/back/feet are rebelling from another plenum extraction.

[Q45tech]

TCS has an extra cooling temp sensor [3 vs just 2 in non TCS cars].

[off2sobe]

Dennis, in your opinion, is there any reason that I shouldn't splice old connector to the new harness?

The connector on the new (installed) harness has a yellow rectangular plug with a wire snap-ring.

[Q451990]

Could you order a new one from Joe with next day shipping and just return the wrong one where you bought it? It would probably be a wash $$-wise, and you won't have to worry about the heat/moisture getting to the splice.

Heath

[off2sobe]

The correct harness is being shipped to me, however, I don't want to have to remove the plenum again just to replace the KS harness. I've got the plenum reinstalled and this is the only connection outstanding.

[DAEDALUS]

A decent crimp job and shrink-sleeving will be more robust than the connection itself. Your car is non-TCS?

[elwesso]

The harness for the under plenum temp sensor is seperate... IT is not with the main KS and CTS harness...

[off2sobe]

Ivory Pearl '94 Q, TCS, 183k. I'm finishing some well-deserved rehab...--valve cover gaskets--spark plugs--knock sensors/harness--plenum/intake cleaning ***Berryman B-12 Chemtool ROCKS on varnish and built-up emissions deposits***--all hoses/plenum gaskets--rad hoses/thermostat ***FYI: UPPER RADIATOR HOSE CONNECTION IS PLASTIC***HANDLE WITH CARE***--drive belts--filters--rear "A" sway bar --front sway bar links/bushings--front brakes--upper links--tension rod (bushings only)

I missed connecting the small coolant hose that connects the throttle body to the dreaded "Y" hoses under the plenum. (Found this when I was filling up with new coolant.) I have a friend that sells equipment to trauma surgeons...he has a 24" clamp devise that should let me get through and set the clamp.

Hence the reason for the post...I don't want to take this apart to replace the harness unless splicing a new plug to this won't work correctly. If there is nothing different in the sensor I will splice and go.

[maxnix]

But per Q45tech's post, there is indeed something different, an extra temperature sensor.

Why try to adapt the wrong part when the correct one is readily available? I can't follow the reasoning here.

[off2sobe]

Maxnix, you either have not pulled a Q plenum or you did not understand my question.

I would like a definitive answer regarding the use of a KS harness designed for a non-TCS Q can be used in a TCS Q (since it was just installed Sunday) by doing one of the following:

1. Change the coolant temp sensor to a non-TCS sensor. (If they function the same, this is a no-brainer).

2. If the sensors function differently (yet to be determined), can we splice a CTS plug from a TCS Q harness to the new (installed, yet incorrect) non-TCS Q harness.

Both harnesses are identical, down to the wire coloring, except for the CTS plug.

[off2sobe]

Followup: Splicing does NOT work. Using the non-TCS knock sensor harness in a TCS Q causes the ECU to receive knock sensor and coolant temp sensor errors. (CTS error lights MIL).

[DAEDALUS]

What resistance measurements did you get from the CTS through the harness at ambient temp?