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-   -   changed ECTS now temp guage not woorking (http://www.saturnfans.com/forums/showthread.php?t=184574)

edefisio 09-16-2012 03:57 PM

changed ECTS now temp guage not woorking
 
I just changed the engine coolant temperature sensor on my 2002 SL2, due to intermittently not starting and based on several posts here. After i changed it, the SES light came on and now the temp guage is not moving at all, though the car did start and seems to be running normal enough. The connector looked to be in good shape, in fact i didn't see any visible problems with the original ects upon removal. Any ideas?

campus189 09-16-2012 06:27 PM

Re: changed ECTS now temp guage not woorking
 
[QUOTE=edefisio;1914858]I just changed the engine coolant temperature sensor on my 2002 SL2, due to intermittently not starting and based on several posts here. After i changed it, the SES light came on and now the temp guage is not moving at all, though the car did start and seems to be running normal enough. The connector looked to be in good shape, in fact i didn't see any visible problems with the original ects upon removal. Any ideas?[/QUOTE]

I take it you visually inspected the connector well?
Are the wires spliced or have electrical tape on them?

edefisio 09-16-2012 07:07 PM

Re: changed ECTS now temp guage not woorking
 
Hi, thanks for the reply...

yes the connector looked fine. no corrosion or anything abnormal.

no electrical tape or signs that it has been replaced before.

The first time I started the car after replacing the sensor, the temp guage pegged all the way to the right for about 15 seconds, then it dropped all the way to the left and the "service engine soon" light came on. and that is where it is stuck at.

is it possible that i got a bad sensor from the auto parts store? I also tried flipping the connector 180 degrees in case that was a problem, and it seemed to snap into place fine, but no change in the gauge.

thanks for any ideas you may have.

magtec 09-16-2012 08:11 PM

Re: changed ECTS now temp guage not woorking
 
[QUOTE=edefisio;1914898]is it possible that i got a bad sensor from the auto parts store?[/QUOTE]

yeah.

dakota1820 09-16-2012 08:15 PM

Re: changed ECTS now temp guage not woorking
 
could have broke the tip loose from the brass portion of the sensor

DonP 09-17-2012 07:22 AM

Re: changed ECTS now temp guage not woorking
 
You also could have received the wrong sensor (not an ECTS).
The 2002 should have had the brass tip ECTS and that is an unlikely failure.
What codes are set?

edefisio 09-17-2012 04:32 PM

Re: changed ECTS now temp guage not woorking
 
yes the original was a brass tip and didn't appear damaged. I changed it figuring it would be a low cost way to see if that would solve my intermittent problem of turning over but not firing. A mechanic had changed the crank position sensor for this same issue a few weeks ago but it started doing it again a couple weeks later. Hopefully I can put my old sensor back to get the temperature guage working again. I will try and post the codes later. Thanks for the input.

fdryer 09-17-2012 05:14 PM

Re: changed ECTS now temp guage not woorking
 
Examine the original sensor and carefully inspect the two pins to be sure they're straight and the wiring harness connector isn't damaged. Now connect the old sensor back on without putting it back into the cylinder head. Just let it hang somewhere. Pull the pcm B+ fuse for a minute to reset the pcm and replace the fuse. Now turn on the ignition and observe the temperature gauge. Hopefully the needle pegging was a simple short that didn't do any harm and resetting the pcm clears any stuck electrons not wanting to move until all power is disconnected.

An electrical short here would be electronically interpreted by the temperature circuit in the pcm as the engine being extremely HOT as in volcano hot. The thermistor would be mistakenly sensing extremely hot temps as very low resistance or a short is the equivalent of a melting engine - the temperature gauge needle pinned all the way to the right even though the engine is cold. Electronically the short is seen as a HOT HOT engine. If no electronic damage occurred internally to the pcm then removing pcm power should allow a nice reset to calm it down for reuse with a correctly connected coolant sensor. The original sensor wasn't the cause of your hard starting problems. Its something else.

Fix this issue first and then continue with troubleshooting other sensors.

edefisio 09-17-2012 11:33 PM

Re: changed ECTS now temp guage not woorking
 
OK, i re-connected the "original" sensor without inserting it into the cylinder head, reset the PCM as you suggested, and turned the ignition on and the temperature gauge came up to about 1/4, so that is a good sign and I guess would imply that i got a bad sensor or wrong sensor from the parts store?

Both the original sensor and the connector looked good with no bent pins or visible signs of damage.

I will need to wait until the car cools down to put the original sensor back into the cylinder head.

As an FYI... The code with the "NEW" sensor is P0117 - "engine coolant temperature circuit" - Low Input.

Thank you very much for the advice!

fdryer 09-18-2012 12:06 AM

Re: changed ECTS now temp guage not woorking
 
Hey! You did good! I do things like that. We call this type of mistake 'destructive testing' to inadvertently see how far things can go bad without breaking anything. Since you didn't break anything like the pcm, back to the problem you started with. Forget the coolant sensor saga. Move on. :cool:

There was a recent post about two different sensors, one for the coolant, the other for air temperature and a member was given the air temperature sensor resulting in incorrect readings when used as the coolant sensor.

Intermittent starting needs more background info; last time plugs were replaced, ignition system cleaned of corrosion, spark tests, fuel pressure test, etc..

DonP 09-18-2012 08:00 AM

Re: changed ECTS now temp guage not woorking
 
P0117 - This DTC detects a continuous short to ground in the ECT signal circuit or the ECT sensor.

Could be youlgot a bad sensor, or a temp gauge sender (used in '95 and earlier models) which is just that, but can be installed as if it were an ECTS. Do you still have the make/part number of it?

Any other driveability symptoms beyond occasional hard starting?

When you say not starting, I presume you mean it would crank but not start.

magtec 09-18-2012 10:03 AM

Re: changed ECTS now temp guage not woorking
 
[QUOTE=edefisio;1915165]...intermittent problem of turning over but not firing. A mechanic had changed the crank position sensor for this same issue a few weeks ago but it started doing it again a couple weeks later.[/QUOTE]

the new crank sensor may have failed.

edefisio 09-18-2012 01:03 PM

Re: changed ECTS now temp guage not woorking
 
OK, i have the ECTS issue behind me as it didn't help and only made matters worse with the shorting problem. I am back to the original sensor.

So the original problem is that the engine will crank and it sounds like it starts to run but immediately dies (just wont idle up). It happens randomly. And if you try enough times and maybe wait a little bit, it will eventually fire up.

Maybe the new crank position sensor went bad? It did go 2-3 weeks without a problem after the new crank sensor was installed, would there be something else causing the sensor to fail?

The car had a complete tune up from the (used to be) Saturn Dealer about 20K miles ago at which time the plugs were changed. I don't know if the ignition would have been cleaned or not and I dont think any fuel pressure tests have ever been performed.

When the car does finally start it seems to run just fine, no idle issues.

thanks everyone for all the input.

fdryer 09-18-2012 01:42 PM

Re: changed ECTS now temp guage not woorking
 
Well, a fuel or ignition issue are left to troubleshoot. Ignition can be as simple as a spark test; check for spark on each plug while cranking the engine. Remove the fuel pump fuse or pump relay to prevent flooding the engine with multiple starts. When plugs are removed, check them for raw fuel - this serves to tell you whether or not fuel is injected. If spark is consistent then the cps is fine. Replace the fuse or relay for a fuel test.

Intermittent spark can mean failure of the cps (not likely if new) or ignition control module. Coil failure affect only two plugs at a time. Junk yard ignition parts are cheaper than new and work just as well.

A fuel pressure check is needed (fuel filter replaced?); turn on the ignition and listen for the fuel pump running for 2-seconds (faint hum/hiss sounds), locate the fuel rail test valve, remove the cap to reveal the schrader valve, cover loosely with a rag while depressing the valve stem expecting fuel to spray out. No fuel or a dribble means a fuel issue; fuel filter, fuse, relay, wiring to pump, pump, pump ground wire. Fuel spray means fuel and pressure are available to the injectors.


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