1985 2.8L ESC ?

Hi there, I just got this truck and it's my first look under the hood.
Its a 1985 S10 4x4 Tahoe 2.8-carb that is 100% stock. (or rebuilt) calif. emissions label #UDW, vin #1GCDT14B4F8194102
The parts and location of controls via Chilton's manual is vague at best. Let alone trouble shooting so it be awesome if someone can confirm a couple things are correct (or not) for me.
It does have a ESC module. It does not have a knock sensor. (searched for a hour easy) The ESC is on the firewall near the distributor. (has a #P2002.8-1) The timing can fail to full advance with no error code. A ESC problem could cause 'spark knock' even at idle when the engine is cold.
Thank you Danny
--end
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wrote:

There is supposed to be a knock sensor in the lower drain plug on block on passanger side. Higher octane fuel will cure spark knock too with sacrificing power too. ----------------- TheSnoMan.com
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hmm, are you sure? I just called the local dealers part counter and then autozone. Both places said it does not have one.
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snipped-for-privacy@pacbell.net says...

Look at Snoballs previous postings here... Notice anything? Yeah just throw everything he just said out. You have no knock sensor.
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Until some other wise asses around here, I was around and driving when ESC came out and they made a big deal about how it worked in media. It uses a piezo eectic crystal to sence motor vibration and it would retard spark some when it heard it. The ESC module (if it really has one) needs a exteranl sensor to hear the knock to begin with and GM used the lower drain hole for it until they placed it under the intake on modular V8 that came out in 99 (where it was easy to change before it is a pain in the butt to change now) You could forgo the ECS and use better fuel or just retard base line spark if you must use 87 octane fuel to limit knock. THere are under informed "children" here in news groups that know nothing about designs and how thing work but they claim to be experts and attack those that may know something that they do not. THe whole idea or concept behind ESC was to allow for mre tolerance of lower octane fuel with higher compression ratios in a attempt to boost MPG and power a bit overall. GM pioneered knock control in early 80's and it is pretty mature today. So mature in fact that it makes people beleive that 87 is all they even need because current generation knock control is so good that it quells knock before you hear it. It is too good really because if it was not there you would know that you need more octane. The problem with this whole concept is though that when it retatrd spark to control it it take away power and MPG because peak cylinder combustion pressure is reached at a less favorable time in crank shaft rotation so less energy is extracted from mixture. Know it alls such as the one who made nasty comment have no really understand of how and why a engine works and how to make it nmost efficent . Their abilty or knowledge is limited to inserting the key and twisting it to make it run and little more. One more thing engine octane requirement are not constant and will increase with tempature and this is why you might get by and car runs great on 87 octane in cold damp weather. THe only reason there is a knock sensor is so that unknowning people such as the comment maker can be blistfully happy on the cheapest gas they can find though most of the time it is actually costing them more to run it in increased fuel consumption and lower power. ----------------- TheSnoMan.com
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By that logic, since I've been brushing my own teeth since 1958 or so, I'm qualified to be a Dentist.

Hooda-haada-wadda? Do you mean "it uses a piezo electric crystal to sense motor vibration?'

That which you deem a "pain in the butt" is another mans skilled trade. On the other hand, jobs for snow plow drivers are always found in the miscellaneous section of the want ads...

Hack repair.

Sez the guy who advocates shit canning that which he can't diagnose.

'Meals Ready to Eat?'

Mid 70s actually.

^^^^^^^^^^^^^ That's a good thing, dumbass!

Gee, too bad GM and the other OEMs can't thumb their noses at the EPA like you do.

Neither do you.

And yours is limited to backyard hack fixes and illegal work arounds.

Can that Parrot say anything else?
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In article <nonelson-A39706.15392320112006

LOL. Wow you actually read that big huge block of letters? I guess they never covered "paragraphs" and "spell checking" in the "mediduh".
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wrote:

Wow! No way am I going to stick my big nose in that battle. But I would like to thank both of you for the help. Both replies really helped me get some troubleshooting information I need in different ways.
Bottom line: TRUE It does have a ESC module. (part #14028830) TRUE It does not have a knock sensor. (searched for a hour easy) FALSE The ESC is on the firewall near the distributor. (Haynes manual) TRUE The timing can fail to full advance with no error code.
Oh boy, now I get to check a unknown wiring harness without accurate schematics. 8(
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Wow! No way am I going to stick my big nose in that battle. But I would like to thank both of you for the help. Both replies really helped me get some troubleshooting information I need in different ways.
Bottom line: TRUE It does have a ESC module. (part #14028830) TRUE It does not have a knock sensor. (searched for a hour easy) FALSE The ESC is on the firewall near the distributor. (Haynes manual) TRUE The timing can fail to full advance with no error code.
Oh boy, now I get to check a unknown wiring harness without accurate schematics. 8(
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Is that part number directly off of the one on your truck? 14028830 cross references to be an EFE relay Looks like this:
http://partimages2.genpt.com/partimages/347322.jpg
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wrote:

Wow, your correct. Thanks
The funny thing is the Chevy parts counter person said that part was a ESC module when I called and said "Can you tell me what this part # 14028830 is?"
I think Heatwave straightened me out.
Thanks again 8)
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snipped-for-privacy@pacbell.net says...

14028830 is a relay that is used for a few diff things. Your Cali emissions 2.8 should have the HEI-EST ignition system.

Correct. I got a 87 2.8L out in the barn (havent hauled the pos off yet) and by that time they actually had a knock sensor. In 85 the 2.8 had 8.5:1 compression. In 87 it went up to 8.9:1. Hence why yours has no need for one.

You're looking at a relay. Your HEI-EST module is in the distributor (7 terminals). A 4 wire pigtail should exit the distributor to link to the ECM. Another big 2 wire pigtail goes to the coil. Are you seeing any of this?

You might have a good schematic once you know what you're looking at. ;-)
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says...

That's has to be it! All the information I have found said this truck has the ESC and it just was making me crazy. Reading your post makes it all add up.
Thanks Dan
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HeatWave wrote:

Seem to remember the one on my 85 T10 was to do with the fuel pump.

VERY true. The 85 I had ate three engines. The original lost compression in the back two holes. Pulled it down and found a bad cam. Did a complete top end job on it and about 10K later it ate number 4 rod bearing. Pulled that one out and dropped a "good" one out of an 89 Camaro into it. Installed an in tank pump and it ran good for the next 15K, Then that engine dropped compression on number 1! Never found a knock sensor on the 85 block and never hooked up the one out of the 89.

Yep HEI with the small cap.

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says...

I need to burn that Haynes manual! $#%% I've never needed to look at GM electronics before now and that manual came with the truck. So I parked my but on the couch went thru the emissions, electrical and ignition sections with a fine tooth comb.
Then I wasted a huge amount of time visually trying to figure out what, where and how for those systems. Going thru the emission's went ok. But look how far off I am on understanding the trucks ignition system let alone troubleshoot it. This trucks was not neglected or modified and so basic I would have been way better off (and done) without that manual.
Thanks to all for everything. Dan
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The manual says what on the cover, 1982-1993? A lot of changes happened in that time frame so if you dont look where you are at in the manual its going to be showing you the wrong system.
You can try subscribing to Alldata http://www.alldata.com/vehicle_owner/index.html Its 25 bucks for 1 vehicle, 15 bucks for every vehicle after that. It beats flipping through a Haynes anyday.
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I hear that. And when you look really close most everything in the ignition section has a "used on most but not all" and located here or here on most but not all models.
That stopped me dead in my tracks. But its out the door now. :)
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My Mitchell On Demand does NOT show an 85 S-10 2.8 w/California emissions as having an ESC system. It DOES show it as having an EGR control module which -might- be confused as being an ESC module.
If you post the number count and color codes of the wires exiting the module in question, I'd be happy to verify if it is the EGR module.
As far as I can tell, this system should be a CCC type system with feedback carburetor and EST, and should be capable of giving flash codes thru the check engine light.
California emissions are different enough that you'd be best off ditching the Chiltons and use only the OEM diagnostic procedures.
Your 2002.8-1 part number is not a GM part number...
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wrote:

Awesome, thanks.
That part 2002.8-1 is a error I made from using the haynes manual. Turned out to actually the a/c relay. The ESC module was actually near the brake power booster.
I gave the parts counter a call just to be sure relay (#14028830) I have in my hand is actually labeled a ESC module and it does not have a knock sensor.. --------------------------------------------------------- ESC module #14028830 (other labels 2-2940 and 5072)
A - pink B - brown C - green and 1 blue/yellow << two wires D - pink/black E - red
The "red" might actually be pink. The "pink" might actually be some other color. The part seems to be a normally closed two pole single throw relay that's sealed so I'm not sure. It looks like one set of contacts open low or both with higher coil voltage. ----------------------------------------------------------
Do you know what A - E should be? T hat would save me lots of time.
My VIN# is 1GCDT14B4F8194102 ca emission control UDW
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