Cancel service engine soon light

[creslevi]

How do you cancel the service engine soon light on a 94 LeSabre ?.

[LeSabre97mint]

Hello

I did a search on the internet and found this link for reading the codes: http://www.obd-codes.com/faq/read-gm...codes-free.php

To reset follow this link: http://www.obd-codes.com/faq/reset_obd_codes.php

Regards

Dan

[HotZ28]

Originally Posted by LeSabre97mint

Hello

I did a search on the internet and found this link for reading the codes: http://www.obd-codes.com/faq/read-gm...codes-free.php

Regards

Dan

Let’s not confuse the 12-pin OBDI connector shown in the link above, with the 16-pin OBDII ALDL (shown below) and used in 94-95 LeSabre (OBD1.5) The procedure described in the link will not work on these cars!

[creslevi]

Hi
Thank you for your response, I had a guy do the scan today and it said TPS (Throttle position sensor) He would have to order it $85.00 !??, Does that sound right to you ?, The one he pointed to on my car is mounted on the left side of the throttle body under another sensor, so close to Exhaust crossover pipe, I don't know if there is room to get a tool on the mounting bolts/screws ?. I think the scanner said Low voltage and it was the only code showing in history or current, When he tried to clear it, it said vehicle not responding, I wonder if that is because you have to change it first ?.
Is there any chance it can just be cleaned and reinstalled ?, or find a good used one in the wrecking yard ?, I have no experience with these, So I would greatly appreciate your opinion.
Thank You Rick

[HotZ28]

He would have to order it $85.00 !??, Does that sound right to you ?, The one he pointed to on my car is mounted on the left side of the throttle body under another sensor, so close to Exhaust crossover pipe, I don't know if there is room to get a tool on the mounting bolts/screws ?.

The TPS runs about $85.00 at most part suppliers. It sound like he pointed to the correct sensor, and normally, the use an offset screw driver is required to remove these.

I think the scanner said Low voltage and it was the only code showing in history or current, When he tried to clear it, it said vehicle not responding, I wonder if that is because you have to change it first ?

No, you should be able to clear the code and see if it comes back. Something is funky here! If the scanner was able to read the code for the TPS low voltage to begin with, it should be able to continue reading data. TPS low voltage does not necessarily mean that the TPS is at fault! This could be a number of problems, including grounds, reference voltage, or even the PCM! It sounds like your mechanic likes to replace parts based on what the DTC’s are! This is not a good basic diagnostic procedure!

Is there any chance it can just be cleaned and reinstalled ?, or find a good used one in the wrecking yard ?,

There is no way to clean the TPS & reinstall! A used one may be good, or it may not! Be cautious when using JY electrical parts, you never know how long they have been sitting in the JY subjected to condensation from harsh environments! (Most of the time, with the hood off)

[creslevi]

Originally Posted by HotZ28

The TPS runs about $85.00 at most part suppliers. It sound like he pointed to the correct sensor, and normally, the use an offset screw driver is required to remove these.



No, you should be able to clear the code and see if it comes back. Something is funky here! If the scanner was able to read the code for the TPS low voltage to begin with, it should be able to continue reading data. TPS low voltage does not necessarily mean that the TPS is at fault! This could be a number of problems, including grounds, reference voltage, or even the PCM! It sounds like your mechanic likes to replace parts based on what the DTC’s are! This is not a good basic diagnostic procedure!



There is no way to clean the TPS & reinstall! A used one may be good, or it may not! Be cautious when using JY electrical parts, you never know how long they have been sitting in the JY subjected to condensation from harsh environments! (Most of the time, with the hood off)

Thanks a Lot for your insight, I will check out the grounds tomorrow(depending on the weather) so far I haven't ordered anything, one symptom I never mentioned before is the last couple days it stumbles pretty bad on an uphill pool.
Rick

[HotZ28]

Originally Posted by creslevi

one symptom I never mentioned before is the last couple days it stumbles pretty bad on an uphill pool.Rick

When is the last time you replaced the plugs, wires, fuel filter and checked the coils resistance? How many miles on this car?

[Blue Bowtie]

Originally Posted by HotZ28

There is no way to clean the TPS & reinstall!

Normally I'd defer to your expertise, but actually, it is possible:



I wouldn't advise it, however, unless you have the facilities for miniature assembly and repair. The bifurcated contacts of the potentiometer wipers are very sensitive and fragile.

Just like repairing you own MAF sensor:



I agree completely that the DTC (error code) does not necessarily mean that the particular item(s) described in the error is faulty. The TPS is relatively easy to diagnose with only a voltmeter/ohmmeter. As previously advised, verify the presence of a correct reference voltage at the sensor, and measure the range of signal from the sensor to the PCM (right at the sensor). The gray wire should be + voltage, black is ground, and the dark blue wire is the signal.

[BNaylor]

Nice show and tell Jeff, however, I agree with Bo in this case and most cases concerning TPS issues. Disassembly is not recommended to the average car owner or DIY type unless you really know what you are doing.

To the OP just check the TPS input and output including linearity as you move the throttle before removing it and/or tearing it apart. Autozone Repair Info has an excellent guide you can use. See link below.

Click here

[creslevi]

Originally Posted by BNaylor

Nice show and tell Jeff, however, I agree with Bo in this case and most cases concerning TPS issues. Disassembly is not recommended to the average car owner or DIY type unless you really know what you are doing.

To the OP just check the TPS input and output including linearity as you move the throttle before removing it and/or tearing it apart. Autozone Repair Info has an excellent guide you can use. See link below.

Click here

Thank you very much for the link to autozone, I printed it out and will try to follow it, You guys are better than the repair manuals,
Rick

[creslevi]

I found my Cables pretty corroded on my 94 LeSabre and the plugged were due to be changed, cleaned the cables and put new plugs in hoping the Service engine soon would reset, It didn't, (The Battery was disconnected about 1 hour)

Now I am back to the TPS, The code was low voltage at TPS, trying to check it with an ohmeter, but not sure what the reading should be at the 2K setting it reads 1.371 and by 1/3 throttle it's down to one with no further reading all the way to full throttle, How sensitive should it be, I don't really understand a lot about OHMs.

I want to check the voltage but not sure how to hook up the leads, I printed out the link at Autozone on the TPS but it's kinda vague on the hookup.
This 94 has 246,000 miles and always ran perfect.
With the TPS plugged in I would have to pierce the wires to check the voltage wouldn't I ?.
Any help greatly appreciated.
Rick

[HotZ28]

Please try to keep your threads of the same subject combined. Your new thread, is now merged with your previous thread on the same subject!

[creslevi]

Originally Posted by HotZ28

Please try to keep your threads of the same subject combined. Your new thread, is now merged with your previous thread on the same subject!

Sorry

[creslevi]

One more thing I noticed yesterday while test driving, No kickdown at any speed, I rarely ever use it, so Don't know if it's new symptom or not, The car run's really strong but the service engine soon light is still on.

I put the ohmeter between the black post and the blue post and got a full range of readings throughout the movement of the throttle, So I guess that means it's not the TPS ?.

[HotZ28]

Originally Posted by creslevi

One more thing I noticed yesterday while test driving, No kickdown at any speed, I rarely ever use it, so Don't know if it's new symptom or not, The car run's really strong but the service engine soon light is still on.

I put the ohmeter between the black post and the blue post and got a full range of readings throughout the movement of the throttle, So I guess that means it's not the TPS ?.

In order for us to help here, it is important that you tell us what the TPS voltage readings are @ closed throttle & WOT. When you say; “I put the ohmeter between the black post and the blue post and got a full range of readings throughout the movement of the throttle”, does not tell us much. This is not enough information for anyone to tell if the TPS is good, or bad!

The TPS is simply a potentiometer used to vary voltage. The best way to check the voltage is with a scanner, but if you do not have access to one, you can use a DVOM. You can probe the terminal with a paper clip to check voltage. The TPS WHITE wire, is the PCM reference signal and should measure 5.0v with ignition on. (Engine does not need to be running) The BLUE wire will show variable voltage from a closed TB position, usually .45v, up to WOT, where it should measure between 4.0v to 4.2v max. Of course, the BLACK wire is ground.

In addition, to verify the voltage that the PCM is using, you must use a scanner! I have seen several throttle position sensors check fine with the DVOM; however, the PCM was altering the reading! In these cases, the reference voltage from the PCM was correct (.5v) and the TPS output was correct, but the PCM had skewed voltage reading and internal failure. When this condition exist, the PCM will need replacing.

Some of the problems you mention here; “No kickdown at any speed”, seem to indicate PCM malfunction. The 94-95 PCM’s are notorious for creating unexplained problems. The #1 cause of PCM failure is voltage spikes! Voltage spikes begin to happen with corroded battery cables, or failing internal voltage regulator in the alternator. I have seen several PCM failures, simply due to removing the positive (+) battery cable before the negative cable(-).