Coolant Temperature Sensor and ECU

[gerpacar]

Have a 92 Talon TSI, the ECU gave a Code 21, which is Engine Coolant Temperature Sensor Fault. OK, I checked the sensor and sure enough it was shorted. Replaced sensor with good unit that was reading ~2500 Ohms at room temperature. Reset the ECU, then started the car, and again code 21. Now, I checked the voltage to the sensor and there wasn't any (0 Volts), the manual says there should be 4.5-4.9 volts. I checked the immediate wiring in the engine compartment and didn't see anything obvious. Could the shorted sensor have shorted out the power source?? Where does the power source for the sensor originate?? Is there a fuse?? Any help would be appreciated! Sorry about the long-winded story, just wanted to get the obvious out of the way.
Thanks

 

[FourG63GST]

I have same problem on my 92GST.

Get coolant temp sensor CEL. Replaced it, and still getting the light.

*Suscribes*

 

[98autogstspyder]

What did you guys do to fix it?

Did the car run better after you changed the sensor?

 

[luv2rallye]

Where does the power source for the sensor originate?? Is there a fuse??

Comes directly and only from ECU pin 20 and there's no fuse. Maybe that wire (yellow green) is shorting to ground (although I don't see how that would burn out the sensor - but it would explain the 0V and the errror code).

 

[crazyfwd]

hi, did any of you guys ever resolve this? i have a similar problem but i get 1.94v to the sensor and coming out of the ecu (yellow/green wire). 91 GS-Turbo

1. tough to start in the morning around 50F ambient
2. throws a code 21
3. will eventually start after a couple of tries
4. very very hard to start on the dsm link
5. have been through 4 different brand sensors.have yet to try oem though

anyone???

 

[crazyfwd]

this morning my car started normal after doing the ff stuff the previous day...

1. replaced about 1 ft of wire coming from the cts and going to the cts from the ecm
2. rewired my msd dis2 grounding points, i wired them directly to battery ground
3. from my msd ground wire, i made another connection to the ecm grounding points
4. replaced coolant temp sensor(can't say this fixed it coz the one i replaced was like 1 year old only and after replacing the sensor and an ecu reset, it was still throwing the cel on)

honestly, i can't say which did it but it sure started real easy the following morning. to those interested, i will post again tomorrow to let you know if the car starts again.

still only getting 1.94v coming from the ecm. fried ecm?


thanks

 

[crazyfwd]

ok, the car started right up for the 2nd consecutive day...two revolutions and she was up and running with good idle to boot(warm uo idle) although mine's a little lumpy coz of the cams.

i'll check again tomorrow and post.

only doing this in the hopes that my experience could help some lost dsm lover's soul somewhere...

thanks and more power!