Service Engine Soon light is coming on........... - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 09-24-2000, 03:32 PM Thread Starter
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Service Engine Soon light is coming on...........

Okay, so far I have changed the oil and filter, changed the coolant temperature sensor, and my buddy cleaned the PCV valve with some electrical cleaner today. Yesterday I changed the o2 sensor. Now, for some reason, when we started it after changing the oil, my SERVICE ENGINE SOON light comes on and stays on. Hmmmm....... It starts, climbs up to 1500 rpm pretty steadily, and then slowly drops down to 800 rpm. Normally, it climbs up to 1100-1200 rpm, then goes down to 800 rpm. What did I do? I changed the o2 yesterday, and I don't think there was a SERVICE ENGINE light. I think I would notice. I've tried disconnecting the positive cable, the negative cable, and now both. Still comes on. What gives? My buddy's dad says that I should disconnect the negative, wait 20 seconds, then reconnect it, and then drive it for about 20 minutes. Sounds logical, but then, would it still be on after I disconnected and reconnected it, or would it go off during the drive? Not to mention, if this does work, what caused it? Any ideas guys?

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post #2 of (permalink) Old 09-24-2000, 04:14 PM
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Re: Service Engine Soon light is coming on...........

my guess would be something with that damn o2 sensor. all those things do is cause trouble! haha. my suggestion would be to try disconnecting the cable for like 20 sec like your buddy said. if that doesnt work, try putting the old sensor back on and see what happens. sometimes, you can just get a bad sensor (ive had it happen before). it could also be the PCV valve maybe but i doubt that if you only cleaned it?? like i said, thats what i would try. have you tried jumpering the terminals to get it to flash the codes yet? if not, do that and see what it comes up with

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post #3 of (permalink) Old 09-24-2000, 04:29 PM
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Re: Service Engine Soon light is coming on...........

take a look at everything you adjusted, cleaned, or replaced. make sure everything is snuggly plugged in. i say undo the battery cable and let it sit for about 10 minutes. i know that it'll wipe you radio and whatever you have set, but it might also wipe out all the old settings the computer establlished. then, take the truck out for a drive and see what happens. it be a good idea to get the codes, that way you can narrow down the possibilities.

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post #4 of (permalink) Old 09-24-2000, 07:47 PM Thread Starter
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Re: Service Engine Soon light is coming on...........

Okay guys. We have checked everything, and it all looks and feels snug. All the wires are hooked up. Disconnected the battery, then took it out for a 20 minute drive at speeds up to 50mph (can't go much faster than that out on the airfield). Drives fine, seems okay in that department. Then jumpered the terminals and read the codes. Says I have a 14 code, which, according to my Chilton's manual, reads as follows:
FOR FUEL INJECTED ENGINE TROUBLE CODES THROUGH 1995 WITH 4L60E TRANSMISSIONS---
DTC AND CIRCUIT----DTC 14- Engine Cooland Temperature (ECT) Sensor Circuit (High Temperature Indicated)----
PROBABLE CAUSE----Sets if the sensor or signal line becomes grounded or greater than 145 degrees Celsius for 0.5 seconds.

Ummmmmm.....I think I did it all by the book. Would disconnecting the positive instead of negative while I did the work matter? I realized I did that, and I didn't reduce the level of coolant because the coolant was cold and I had a fresh bottle of coolant handy. Any help and ideas would be great. Thanks guys [img]/wwwthreads_images/icons/tongue.gif[/img]


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post #5 of (permalink) Old 09-24-2000, 08:23 PM
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Re: Service Engine Soon light is coming on...........

My check engine light came on at 75K miles and stayed on for a day or so....truck ran fine...and I looked at most of the stuff you looked at...light went off as mysteriously as it came on...I have 107K and it has never come on again since...(Til in the morning when I start it to go to work...Murphys law)...I know this is no help whatsoever, but I'm just as curious as others to understand the cause...'specially since there is nothing obviously rwong anywhere...JD

post #6 of (permalink) Old 09-25-2000, 01:21 AM
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Re: Service Engine Soon light is coming on...........



Andrew-

That code means that when you changed the sensor, you might have got some RTV on it, or antiseize, and it's not sending the proper voltage to the computer. Disconnecting the negative cable will wipe out the computer's memory, then it re-learn's everything. Keep in mind, how you drive it afterwards effects how it will reprogram itself. As far as the sensor, I would take it out, look at the pigtail as well. If anything blocked, the sensor will not function correctly, and will throw a code.

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post #7 of (permalink) Old 09-25-2000, 08:41 AM Thread Starter
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Re: Service Engine Soon light is coming on...........

Hmmmm.....I didn't use any anti-sieze on it, that probably would have been a good idea though. We've done all that disconnecting battery cables and checking the codes stuff. Just keeps flashing 14, so I guess I should take it out and clean it off. I'll do that tonight. Thanks.

Oh yeah, and my gauge is still wrong, only got up to 140-150 or so. The radiator was hot to the touch, it feels like it is working properly. Which is the part that sends info to the gauge, the coolant temperature sensor or the coolant temperature sender?

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post #8 of (permalink) Old 09-25-2000, 10:50 AM
 
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Re: Service Engine Soon light is coming on...........

Normally the O2 sensor comes with "Conductive Anti seize stuff" did you use it?

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post #9 of (permalink) Old 09-25-2000, 05:38 PM Thread Starter
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Re: Service Engine Soon light is coming on...........

I did on the o2, it came already applied on the Bosche sensor. The coolant temp sensor didn't, and I didn't think to with all the coolant rushing out. [img]/wwwthreads_images/icons/crazy.gif[/img]

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post #10 of (permalink) Old 09-25-2000, 10:11 PM
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Re: Service Engine Soon light is coming on...........

coolant temp sender controles the guage.

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