Help!! No 5 volt signal at injector plug
 

hi guys,,i have a 94 sc2 that is getting no 5 volt signal to the coolant temp sensor,,i have just replaced that sensor plus the crank sensor,,fuel psi is good plus my fuses and relays are all working ,,my question is what is my next step to figure out the cause of no voltage,,,thxs for the help..

The yellow wire is the "hot" lead for the engine coolant temp sensor (ECTS). It comes directly from terminal C12 on the Powertrain Control Module (PCM).

Normally, I suggest replacing the ECTS connector at the same time you replace the sensor itself (OEM parts only, please) ... costs a bit more for parts, but things tend to work properly the first time.

and he does mean OEM parts only. Meaning do not buy the etcs from PetesParts&PartySupplies.

DEALER ONLY for ETCS and Connector

ok point taken regarding the connector,,,i have checked the connector and im geting a 5 volt reference signal to the connector,,i did notice that the connector part of the sensor spins if you try to turn it,,i dont want to sound stupid but im assuming that since its a 2 wire connector, the sensor is broken right??please advise,,,thanks guys

Hi there, PaulEdgar --

Short answer here --> Yep, the sensor is broken. Might have happened when you (tried to) put the old connector on the new sensor. Anyhow, you need to make another trip back to your local Saturn-friendly DEALERSHIP, and purchase an OEM sensor and associated electrical connector. Make sure you get the sensor with the metal tip ...

ok thanks for the info oceanarcher,,,if this does not fix my issue,what would be my next step if the sensor n connector dont fix it..possible ecm?a broken ground from the ecm?

Confusious once said something about worrying and rocking chairs --> it gives you something to do, but accomplishes nothing. Get your new sensor and associated connector properly installed and hooked up, then we can discover whether we need to go looking for "what ifs" ..........

ok oceanarcher,i bought a factory sensor and pigtail and replaced it and now the car will start but,my coolant light comes on and the check eng light as well,it says its a code 14 which is a issue with the sensor...??? im at my whits end with this car,,,what should i look for or do next,,,thxs for your help..

Well, first thing I'd do at this point, is to carefully disconnect the ECTS connector.

Leave the engine shut off for the next couple of tests.

Using an ohmmeter with long leads, I'd measure BLACK wire from the ECTS connector back to the Powertrain Control Module, contact C3 (should read zero ohms, or very close to it).

Now, read the YELLOW wire from the ECTS connector back to the PCM, contact C12 (again, it should read zero ohms).

Now, read the ECTS itself from terminal to terminal (should be between 100 ohms and 3,000 ohms, depending on ambient temperature)

Please let me know what you find ................

ok well i measured the resistance in both those wires and both read zero and the new sensor i put in reads about 2000 ohms

Isn't there a sensor in the bottom of the overflow jug on these Saturns? If so, maybe that's the problem. I know some vehicles have them, but I'm not sure about the Saturn.

yes there is but code 14 is specific to the ECTS --- out of range high

well everything checks out according to my manual specs,,question,,when they say measure the resistance of the ground circuit of a wire does that mean back probing that wire or can i test that ground by connecting one wire from a multimeter to a ground and the other wire from it to the wire im testing??? the reason besides me sounding stupid for asking that is i read that if the module isnt sending a signal to the pcm, then the injector will not fire,,

There is a coolant light that senses the water level in the plastic tank up against the passenger side fenderwell. That light means the water level is low with in that particular tank however it has nothing to to with engine temperature or the gauge. It is strictly a low coolant sensor. It seems to me that might be the light you are seeing. If the tank become cruddy it clogs up that sensor and flushing it out generally cleans the sensor up so that if functions, if the tank is full. If the tank is empty, or low it is not lying to you.
However a code 14 is a coolant temperature sensor signal is low. Which may mean it has not cleared yet from the previous problem.

Lemme stick two cents in here and hopefully not confuse things.
These measurements you made:
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ok well i measured the resistance in both those wires and both read zero and the new sensor i put in reads about 2000 ohms
===============
Indicate that each wire is complete between the points you measured it from. That is if one end and the other was the pin connection in the connector they are indeed good between the pins.
The measurement of the sensor is about right as stated depending on the temperature of things at the time the measurement was made.

It is now an assumption that when everything is plugged in the sensor will be seen or sensed by what ever it is plugged in to.

in essence, this statement, the request to make the measurements:

Well, first thing I'd do at this point, is to carefully disconnect the ECTS connector.

Leave the engine shut off for the next couple of tests.

Using an ohmmeter with long leads, I'd measure BLACK wire from the ECTS connector back to the Powertrain Control Module, contact C3 (should read zero ohms, or very close to it).

Now, read the YELLOW wire from the ECTS connector back to the PCM, contact C12 (again, it should read zero ohms).

Now, read the ECTS itself from terminal to terminal (should be between 100 ohms and 3,000 ohms, depending on ambient temperature)

Please let me know what you find ................
===========================
The assumption now becomes if the sensor was plugged in and you went to the PCM contacts C12, the yellow wire and PCM contact C3 the black wire and measured the resistance you should be able to read the aprox. 2000 ohms indicating that the sensor is attached and the readings should be good at C12 and C3

What it does not tell you is if there is damage to the PCM at those points internally that will keep the reading from being read and thus processed.

It also does not tell you if either of those wires are some how damaged where the insulaton is cut or something so that the wire itself is touching bare metal of the car. Thus as they say grounded out. This would also affect the reading when plugged in and the circuit is now trying to be functional.

I don't fully understand your question on measuring the ground ckt of a wire. That can mean a lot of different things in the way it was asked.
But assuming that a wire, one of the two the black or yellow is some how damaged so that the wire itself touches the metal of the car, thus grounded, measuring the resistance of the wire from either end (it makes no difference which end as you have determined that the wire in complete from one end to the other) and with both plugs unplugged you are now looking to see if the wire is touching metal some where thus affecting the operation of the curcuit. This is done by setting your meter to read maximum resistance and then placing one probe on something that is metal and has a good conntection or the - post of the battery and the other probe on each of the pins of the connector the reading should not change. Why? Nothing is plugged in and if there is not short or grounding of the wire it is considered as "open" to ground thus good.

Now with this test that has determined as best as one can that the sensor is good (individual test of the sensor) the wiring is good )individual testing of the wires at a connector) that when plugged in the sensor can be seen at the PCM ( the resistance measurement at pins
C3 and C12 being something like 2000 ohms or so as indicated)
If the error code continues, that seems to indicate that some how the PCM cannot process the data being sent to it.
That indicates a bigger problem.
And yes, your reading of this statement is true:
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the reason besides me sounding stupid for asking that is i read that if the module isnt sending a signal to the pcm, then the injector will not fire
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I think, but it is not stated well at least as I understand things, a problem when working on a forum thread. What module are you talking about?
No the question is not stupid, The PCM looks at a number of factors and when they are correct or with in an operating band anyway determines how much fuel to inject and when to fire the injector and the spark plugs and a number of other things.
And the error code says something is not correct.
And there in lies a problem.
The electronics of the PCM are very reliable and considering the age of the car and the number of them including anything remotely similar made by GM the reliability factor of the electonics is huge, And unless you have a very expensive scan tool that allows you to take control of the PCM and tell it to do certain things the best you can do is determine as you did that the wiring is good and the sensor is good and if it still does not work properly it is time to consider changing the PCM as the next step and that is not a recommendation I can make sitting where I am at this point in the trouble shooting sequance. It is both expensive and pointless if it is not going to solve anything.

sorry i was confusing about what module..i was referring to the ign control module..someone told me that that module sends a signal to the pcm,,i did test the wires and according to my shop manual the numbers are within specs...im about to stick a road flare in this dam thing lol...

I understand your frustration. Even a 1994 Saturn is a complex computer controlled car that can have extremely frustrating problems. You have to go back another 15 years to get out of computer control and get to just electronic ignition and a feedback carburetor of course with that change you also get miles of vacuum lines which computor replaces and then another 10 years to get to something basic.

The Saturn uses to two sensors on the passenger side of the cylinder head.

On tells the computor what the temperature of the engine is and that is used to determine how to run the engine and is also used to supply information to the gauge to display temperature. What is the gauge saying is going on?

The other simply runs the electric fan.

This is about the time the suggestion is made to go to your auto-parts store and buy or order a Chilton, motor, mitchells or what ever service manual to give you some insight as to what is taking place. About $25.00 US.

Except I guess, you already mentioned you had one. Ooops!