Help!!! P0117 & P1493

[GSTurbo05]

I was going to work on thursday and suddenly 2 blocks from my job my cars CEL comes on with the battery light, so im thinking its the battery or alternator. So i take it to Autozone and grab the code reader and it reads P0117 meaning the ECT sensor voltage is to low, Another code poped up aswell P1493 Bttery temperature sensor voltage to low
I replaced the ECT sensor and the code still pops up, Also my fans are driving me nuts they wont shut off, even when you cold start they start right up. I dont even know where the hell the battery temperature sensor is located, the guy at autozone said it my be affecting my ECT sensor if its not replaced. How am i supposed to raise the voltage???
Can anyone help me? has anyone had this problem before???

Just to mention its on a 1996 Eclipse RS

 

[Doug99RS]

I was going to work on thursday and suddenly 2 blocks from my job my cars CEL comes on with the battery light, so im thinking its the battery or alternator. So i take it to Autozone and grab the code reader and it reads P0117 meaning the ECT sensor voltage is to low, Another code poped up aswell P1493 Bttery temperature sensor voltage to low
I replaced the ECT sensor and the code still pops up, Also my fans are driving me nuts they wont shut off, even when you cold start they start right up. I dont even know where the hell the battery temperature sensor is located, the guy at autozone said it my be affecting my ECT sensor if its not replaced. How am i supposed to raise the voltage???
Can anyone help me? has anyone had this problem before???

Just to mention its on a 1996 Eclipse RS

The 2gnt doesn't have a battery temperature sensor. The test for this particular code is asks if the code has a run count of zero (as is does this code come back every time you hit the key) and if so, for this vehicle, replace the powertrain control module (PCM).

After getting past that bad news we can back-track a little on the Battery temp code itself and the ECT code.

There is a possibility that the computer in the car came out of a neon. It should plug right in and probably work and you wouldn't know any difference. The Battery temp sensor is located in the battery tray on the neons but if unplugged won't normally turn on the check engine light. The computer only looks at this sensor at key on after about 8 hours of cool down. Outside of that it doesn't really use it again.

The engine coolant temperature sensor on the other hand is a bit more involved. It's a two wire sensor that shares the ground with multiple other sensors. If one of them is back-feeding any voltage then it could throw the computer a little off. You should check the ground circuit using a test light attatched to battery positive. If it lights up brightly then your ground is good.

The sensor circuit should have 5 volts on it when you unplug it. If you don't have 5 volts then you need to check it at the computer itself because it's responsible for sending out the five volts.
Doug

 

[GSTurbo05]

WOW out of a neon huh? I was ripped off. but im still very lost, would it be best to find a used PCM and install it? Alright my dad has a test light now i connect the lil aligator mouth thingy to the battery positive and the needle to wich ground? the one where the sensor leads to or the one near the pcm? if you have a diagram would be great thx doug oh and what about the whole fans thing saying on forever?

 

[Doug99RS]

So it has been replaced?

 

[GSTurbo05]

Doug when i bought the car it had that ecu in it already, the dealer supposably told me that it was a trade in. It was my first car before my GSX, So the ecu must have come out of a neon.

 

[Doug99RS]

That's not totally conclusive though. Can you get the part number off of the case for me? I might be able to run it and see what it belongs in.

Regardless, do you have a multi-meter and do you want to run through some tests before throwing a PCM in it that may not be needed?
Doug

 

[GSTurbo05]

That's not totally conclusive though. Can you get the part number off of the case for me? I might be able to run it and see what it belongs in.

Regardless, do you have a multi-meter and do you want to run through some tests before throwing a PCM in it that may not be needed?
Doug

I actually dont have amulti meter. you want the numbers off of the ecu right?

 

[GSTurbo05]

Here you go the numbers from the casing are :


4651711-2
64490
2

Those are the numbers i pulled off of the silver part of the case.

 

[Doug99RS]

I searched that part number and it's inconclusive. It said there were no updates for it. Most of the time it will show updates or that the part number is invalid. The original part number on that case SHOULD require at least one software update so something's not washing. Can you take a picture of the part number label?

Also, without a multi-meter I can't help you much more from here. A mutlimeter is a real must in order to do even the most simple of tests here. You should go gget one from Sears or somewhere for about $30.00. It would be alot cheaper than a replacement computer that may not even be needed.
Doug

 

[GSTurbo05]

alright ill take pics here you go...........

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

Oh my dad has a multimeter

 

[Doug99RS]

That was a casting number for the case. Were there any other numbers/labels/anything else on there that could identify it? Most of the time there's two sets of numbers. A serial number and a software number. Let me know when you've got the multi-meter in hand and I'll throw up some quick chceks for you to run through. Should be real easy to understand.
Doug

 

[GSTurbo05]

unless there is more under the casing then no thats the only numbers on their.not even on the black side, theirs no labels at all. Ill have to ask my dad for the multimeter.Go ahead and make me a list of the things you would like me to check and how and ill tell you tommorow night, thank you doug

 

[Doug99RS]

The engine coolant temperature sensor uses a two wire connector. The computer puts out 5 volts on the signal wire (Dark Green with a white tracer) and measures how much of that 5 volts goes to ground. The ECT sensor is basically a pair of resistors. Long story short the resistance is high while the engine is cold and resistance is low when the engine is hot. The transition between hot and cold should be smooth and gradual respective to temperature.

Checking this is real easy. With the engine off but key on, ect unplugged you should show 5 volts on the signal wire. Resistance to ground should be less than 5.0 ohms. If you don't have 5 volts then you either have high resistance in that circuit OR the computer is not putting out the right voltage.

Checking signal wire side:
High resistance in the circuit can be caused by corrosion or incomplete wiring, another sensor that has high resistance that shares the circuit (not in this case since this ECT wire is a dedicated signal wire) or corrosion in connectors such as at the PCM or the sensor itself.

The computer could be bad causing the voltage not to be right, the grounds for the computer could have high resistance or the power circuits feeding the PCM may not have enough voltage on them to bring the reference voltage up to where it needs to be.

To check this you will want your meter in the voltmeter mode and check at the sensor first. If you've got 5 volts then your computer (for this circuit alone) is good and you need to consider other failure of the PCM or a problem with the ECT sensor or ground circuit. If you don't have 5 volts jump straight to the computer and find the correct other end of the wire you just checked. It's pin 26 at the PCM. Check resistance on that circuit and if it's fishy let me know I can go in to further diagnostics with it. If it checks fine then you are PROBABLY ok there.

Checking ground wire side:
The best way to do this is kinda confusing but it basically involves using a test light. I could spend an hour explaining that one. But just for simplicity you will want to check resistance again from the sensor to the PCM. I'm fairly certain that the sensor ground is shared with other sensors so if you're having a problem on that circuit you would probably have other sensors throwing codes as well.

Summary:
You should have 5 volts at the sensor connector and a good ground. If you DO then you've got a bad sensor again or a bum computer. Personally, sensors are cheaper than a new computer, I'd give it a shot.

Oh, and you're sure there's not a white lable anywhere on that PCM? I thought they used to be opposite of the connectors.

 

[GSTurbo05]

***UPDATE*** I was to stupid to know how to use the multimeter so heres a pic of it and at what setting am i supposed to use it. another thing if i was doing it right, the multimeter would stay at zero. I doubt i did it right. Another thing i checked the ground on the connector plug and the light lit up as well, i tested the same ground wire on the ecu wich should be pin #2 black with a blue streak wire and it also lit up the light. So i take it my ground is good? Well heres the pic of the multi meter.

You must be logged in to view this image or video.

 

[GSTurbo05]

Doug where are you i need your help!!!!!

 

[Doug99RS]

The meter needs to go to the 20 DC v range when you're checking for the 5 volts.

I beleive it needs to go to the 200 ohm area when checking resistance but don't quote me on that. My meter is auto-ranging and I don't have to worry with multiple settings for resistance.

Also, I can't see the writing for the other socket for your positive lead. I THINK you've got it in the wrong socket because that's for checking amperage. If you could move the leads around and get a glare-free pic I can tell you for sure.

I'll be at work all day so I won't be back on until after 6pm EST.
Doug

 

[GSTurbo05]

***UPDATE*** So you were right the positive was on the wrong side socket. Now doug heres the numbers i got for the volts on the ECT sensor plug

Positive : 5.14v
Ground : 7.77ohm's


Thx for all your help doug.

 

[Doug99RS]

7 ohms of resistance? That's quite a bit. I've got to run but you might be on to something there. I'll take some books with me to the place I'm staying at tonight and hopefully I'll be able to post something else up for you.
Doug

 

[GSTurbo05]

**UPDATE** Those last voltage and resistance numbers could be wrong, i got those numbers with the key on ACC right before you start the car, I did the test over again with the car completly shut off and these are the new numbers.

ECT plug :
Positive : 0.06-0.07
Resistance : 4.65 ohm's

ECT Sensor : 1.76 ohm's while car was warm, thinking 30 celcius.

Car Battery is reading 13.25ohm's

Maybe that will help

 

[Doug99RS]

You should be checking for voltage and grounds with the key in the on position. The computer will not supply voltage to the sensor without it being powered up. I'm not sure but there's a possibility that the computer may also open and close path to ground based on whether or not it's powered up.

Key on (passed the acc position with all your guages lit up), engine off you should have 5 volts going to the sensor. You should also have little to no resistance to ground on the ground circuit. The resistance on the sensor looked fine.
Doug

 

[GSTurbo05]

ahhh ok then the first reading are right i did have it passed the acc on key on with the gauges lit up, kinda like when you check for a code on a code reader. Alright so did you come up with anything for that high resistance?

 

[Doug99RS]

ahhh ok then the first reading are right i did have it passed the acc on key on with the gauges lit up, kinda like when you check for a code on a code reader. Alright so did you come up with anything for that high resistance?

I have some ideas but they all require other test results to be revealed first.

 

[GSTurbo05]

Um ok? Is it ok if i know what tests are needed? Do you have AIM or Yahoo messenger? would be much easier.

 

[Doug99RS]

Um ok? Is it ok if i know what tests are needed?

It's the ones you've already done before when you had the key in the acc position.

Basically... I need to know:
What voltage you have at the sensor signal wire at the sensor connector.
How much resistance to ground you have at the ground circuit wiring at the sensor connector?
And finally how much resistance there is on each wire from the sensor to the PCM connector pins.

It may sounds complicated but it's really not. Once you have the results from that test I can give you one or two more methods to double check and then we should be able to come to a final diagnosis on that together.
Doug
I do have an instant messager service but I don't have time right now to get on there. I've got a honda (boo!!) to go fix.

 

[GSTurbo05]

Ok doug dont get offline give me a few minutes let me run those tests, ill be right back.