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1997 chevy 2500 giving p0118 code
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monyonyo
New User
May 9, 2014, 12:59 PM
Post #1 of 10
(4069 views)
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1997 chevy 2500 giving p0118 code
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my 1997 Chevy 2500, 5.3L vortec, 270k miles, check engine light came on accompanied by rough idle, black smoke, hard start esp after warm up. The code for the check engine is p0118. So far I have replace the ect sensor, check the sensor wire to the pcm for shorts, and even replace the pcm. I had the new pcm flashed to my truck's VIN. I am still getting the engine code (plus symptoms). The voltage at the sensor connection is 11.5 v. The sensor resistance at 190 degress engine temp is around 250 ohms. Now I am lost. I can use some troubleshooting advice.
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Discretesignals
Ultimate Carjunky
/ Moderator
May 9, 2014, 1:06 PM
Post #2 of 10
(4066 views)
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Re: 1997 chevy 2500 giving p0118 code
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5.7L?
The voltage at the sensor connector is way wrong. If you are checking the voltage with the sensor unplugged on the signal wire (yellow wire), it should be around 5 volts. You got to have a short to 12 volt power in that signal wire somewhere.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 9, 2014, 1:10 PM)
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monyonyo
New User
May 10, 2014, 3:47 AM
Post #3 of 10
(4032 views)
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Re: 1997 chevy 2500 giving p0118 code
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yes 5.7L 
The PCM pin out chart indicates the red connector pin number 23, yellow wire and I confirmed that. The wire to the sensor from the wire harness bundle is dark green. Can you offer insight to this color change and would it likely be the yellow from the PCM or the green that has the short. Do I have to open the entire wire harness bundle to check this wire? Is it possible that the short is under the dash? I don't know the proper way to check voltage at the PCM so I haven't tried to see output voltage.
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Discretesignals
Ultimate Carjunky
/ Moderator
May 10, 2014, 4:18 AM
Post #4 of 10
(4027 views)
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Re: 1997 chevy 2500 giving p0118 code
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According to the schematic the wire is yellow all the way from the PCM to the sensor with no connectors in between. If it changes colors, that could indicate someone at one time had repaired the circuit by doing a wire overlay.
The only way your going to find out how that wire is getting 12 volts on it is to inspect the harness all the way from the sensor to the PCM. Look for anything obvious or maybe were someone had done some harness repairs.
I know for a fact that yellow wire is supposed to have around 5 volts on it with the ECT connector unplugged.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 10, 2014, 4:19 AM)
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monyonyo
New User
May 10, 2014, 6:02 AM
Post #5 of 10
(4018 views)
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Re: 1997 chevy 2500 giving p0118 code
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Should I see continuity between the yellow wire at the PCM (pin 23) and the green wire at the sensor end? Because I dont.
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kev2
Veteran
May 10, 2014, 6:14 AM
Post #6 of 10
(4017 views)
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Re: 1997 chevy 2500 giving p0118 code
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1997 its been awhile I remember there were 2 ECT sensors -
your mentioning Dkgrn wire has me thinking -
the single wire (Dk/Grn) was the gauge sensor.
the 2wire blk/yel was the ECT for the PCM - you need to change the 2 wire sensor.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 10, 2014, 6:30 AM
Post #7 of 10
(4016 views)
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Re: 1997 chevy 2500 giving p0118 code
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#4 is for the gauge. #8 is the one you are looking for.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
May 10, 2014, 10:27 AM
Post #8 of 10
(4010 views)
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Re: 1997 chevy 2500 giving p0118 code
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Kev and HT might be on to something. I never considered you could be looking at the wrong sensor. The gauge sensor connector green wire will have 12 volts on it.
He probably has the whole harness ripped apart.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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monyonyo
New User
May 10, 2014, 12:14 PM
Post #9 of 10
(4004 views)
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Re: 1997 chevy 2500 giving p0118 code
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Oh. There's a difference between sensor and sender. Imagine that. I didn't open the harness. I took a long look at it and said, "Oh hell no. Time to give up and take it in!" Thank you for your assistance. I replaced the sensor (this time) and all is well. Problem solved. The troubleshooting guide I was using makes a heck of a lot more sense now. Took me all of 15 minutes. Talk about over thinking a problem.....shech.
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Discretesignals
Ultimate Carjunky
/ Moderator
May 10, 2014, 12:39 PM
Post #10 of 10
(4000 views)
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Re: 1997 chevy 2500 giving p0118 code
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Thank goodness Kev and HT came to the rescue on this one. Good catch!
Thanks for the follow up. Closed as solved. Can be reopened upon request by the OP
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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