yes im in need of help in which wires off both my coolant sensors corresponde to which connectors and pins in the pcm to test the conductivity to see if i have breaks in the lines. couldnt find any diagrams to help bc i have the p0118 code and have changed radiator due to gunk and both hoses and both sensors and t-stat light went off but came back on after a 2.5 mile drive
i have a 96 blazer 4.3 4wd if needed to know

 

i have done everything i know possible.... just got done testing the wires black and yellow from the sensor to the pcm or big black box with a bunch of wires going to it, they tested good meaning no breaks in the wire so i guess my issue is the pcm not reading or sending enough volts to the sensor.... does this mean i need a new pcm?
the wires ran to two different plugs mine being......

the black wire ran to red 3 which is a 32 pin plug that was on top first plug going from left to right

and the yellow was a red plug red 1 first plug from going left to right on the bottom
(this is if you got it off and looking straight at the back of it)
Im in a bind and dont know what to do....... any suggestions are greatly needed thanks

 

Should be 5V going to the sensor. The ECM reads what it gets back out of the 5V it sent.

Is the coolant temp getting up to 190° + ? If your T-stat isn't closing properly, it will never warm up enough to get out of open loop.

 

yes sir it is warming up correctly, always between 190-210 (it takes around 15-20 min of driving to get this temp) on the guage i havent tested the actual set voltage to the sensor, just test the wires for breaks

is there a way to test it with a multimeter without having to by a expensive scanner?

could i test the plug terminals of the sensor when it is unplugged??

 

Don't need anything fancy to test for the 5V reference. A multimeter or even an analog meter will suffice. Wouldn't hurt to test the sensor itself as well. The resistance should drop as the engine warms up. Also make sure the 2 pins didn't get bent on top of the sensor.

 

Grab a Haynes Repair Manual book #24071
It will have the schematic diagram you need inside.. Works with:

Chevy S-10 & GMC Sonoma Trucks (94-04)
Chevy Blazer & GMC Jimmy (95-04)
GMC Envoy (98-01)
Olds Bravada & Isuzu Hombre (96-01)

 

Assuming you have two coolant sensors, here's an insider's secret on how to determine which one is the one for the ECM.
Once engine is warmed up and temp gauge shows it, pull the connector fro one of them. If temp gauge drops to Cold, it's the other one. If nothing happens to the gauge, it's the one you disconnected. Measure voltage at that connector. Should read 5v {v-ref}. If it has 5v.. then ohm the sensor.

Dont tell anyone I told you..

 

thanks smitty like i said im in the process of chasing down this problem and believe it is the voltage being sent to the sensor
because ive went through 2 sets of sensors to make sure. everything seems to run fine other then this code (p0118) which is causeing the miss.

-also to add i took all connections to the computer and sensors and cleaned them.
so i will look for bent prongs on the sensor and test the voltage thanks everyone for the advice
peace,love, and chicken grease

 

i test the prongs to the sensor and got a 10.1 reading
(unplugged the sensor connected my test leads and started the vehicle after it sit overnight)
go a reading of 10.1 volts which ive im correct is double then what it is expose to be?????

 

That's a stumper ....

I'd try and find another computer to borrow to try out before spending the dough on another one - usually the computer is the last thing to malfunction, but it does happen. I hate just replacing them without knowing 110% that it's bad.

If you have a buddy with the same truck .... or are in good with a junkyard, maybe you can throw one in & re-test ....