'86 ECM - what's it do? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Brad_Olson · 03-21-2005, 08:36 PM

I have an '86 K10 with a carbureted 305 and 4-speed manual transmission. The Q-Jet is the non-computer variety (M4ME) and the HEI has a vacuum advance canister and a 5-pin module. I'm guessing that the 5th pin is somehow tied to the ECM that's located under the dash behind the glovebox; does anyone know exactly what it and the ECM do? I did a minor distributor overhaul over the weekend and after reducing end play the timing's a bit more advanced; would this cause any problems for the ECM? Thanks!

Brad

jermasaurus · 03-21-2005, 11:53 PM

If you say that the 5th pin from the distributor goes to the ecm, I would say it retards the timing with the input from the knock sensor.

Brad_Olson · 03-22-2005, 09:30 AM

Hmph. That sucks. Anyone know if it's possible to somehow override this so that the ECM's out of the picture and the timing is only as how I set it? Perhaps a conversion to a 4-pin HEI is in my future...

Brad

**N2TRUX** · 03-22-2005, 09:34 AM

Quote:

Originally Posted by Brad_Olson

...... Perhaps a conversion to a 4-pin HEI is in my future...

You already answered your question. To eliminate the ESC you have to install an standard HEI distributor...

MylilBowTie · 03-22-2005, 09:38 AM

http://www.73-87.com/7387garage/drivetrain/escrepl.htm

That might help you out.

Slonaker · 03-22-2005, 01:11 PM

Quote:

Originally Posted by MylilBowTie

http://www.73-87.com/7387garage/drivetrain/escrepl.htm

That might help you out.

Make sure you read down to the bottom of the page. There are instructions there for converting an ESC distributor to a regular one. Instead of replacing it with a regular one, you can remove the ESC functionality by clipping and soldering a couple of wires.

Slonaker

Brad_Olson · 03-22-2005, 01:15 PM

Many thanks for the replies! Since I'm not sure how long I'm going to keep the truck I'll probably do the quick/short ESC disable for now, but if it looks like long-term ownership is in the future (the idea of swapping my '78 C10 cab and box to the '86 K10 frame has crossed my mind more than once) I might completely remove the ESC controller and convert to a 4-pin HEI. Thanks again!

Brad

tommy knotts · 03-22-2005, 11:12 PM

disconnect the connector on the hei,ond cross terminal A and C on the lead comming out of the HEI.it will work fine

Brad_Olson · 03-23-2005, 10:40 AM

So you're saying to leave the connector disconnected and jump the A and C wires? I reread the 2 conversion routines mentioned above and notice that nothing's said about the connector being connected or disconnected, so now I'm wondering what the B and D wires do and if they're necessary with A and C jumped.

Brad

tommy knotts · 03-23-2005, 10:44 PM

yes leave disconnected,cross A&C,leave original module in dist

03-21-2005, 08:36 PM	#1
Brad_Olson Active Member Join Date: Mar 2005 Location: Stoughton, WI Posts: 187	'86 ECM - what's it do? I have an '86 K10 with a carbureted 305 and 4-speed manual transmission. The Q-Jet is the non-computer variety (M4ME) and the HEI has a vacuum advance canister and a 5-pin module. I'm guessing that the 5th pin is somehow tied to the ECM that's located under the dash behind the glovebox; does anyone know exactly what it and the ECM do? I did a minor distributor overhaul over the weekend and after reducing end play the timing's a bit more advanced; would this cause any problems for the ECM? Thanks! Brad

03-22-2005, 09:38 AM	#5
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	http://www.73-87.com/7387garage/drivetrain/escrepl.htm That might help you out. __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

03-21-2005, 11:53 PM	#2
jermasaurus Registered User Join Date: Dec 2004 Location: New Lenox, IL Posts: 442	If you say that the 5th pin from the distributor goes to the ecm, I would say it retards the timing with the input from the knock sensor.

03-22-2005, 09:30 AM	#3
Brad_Olson Active Member Join Date: Mar 2005 Location: Stoughton, WI Posts: 187	Hmph. That sucks. Anyone know if it's possible to somehow override this so that the ECM's out of the picture and the timing is only as how I set it? Perhaps a conversion to a 4-pin HEI is in my future... Brad

03-22-2005, 01:15 PM	#7
Brad_Olson Active Member Join Date: Mar 2005 Location: Stoughton, WI Posts: 187	Many thanks for the replies! Since I'm not sure how long I'm going to keep the truck I'll probably do the quick/short ESC disable for now, but if it looks like long-term ownership is in the future (the idea of swapping my '78 C10 cab and box to the '86 K10 frame has crossed my mind more than once) I might completely remove the ESC controller and convert to a 4-pin HEI. Thanks again! Brad

03-22-2005, 11:12 PM	#8
tommy knotts Senior Member Join Date: Dec 2004 Location: tunnelton WV Posts: 325	disconnect the connector on the hei,ond cross terminal A and C on the lead comming out of the HEI.it will work fine

03-23-2005, 10:40 AM	#9
Brad_Olson Active Member Join Date: Mar 2005 Location: Stoughton, WI Posts: 187	So you're saying to leave the connector disconnected and jump the A and C wires? I reread the 2 conversion routines mentioned above and notice that nothing's said about the connector being connected or disconnected, so now I'm wondering what the B and D wires do and if they're necessary with A and C jumped. Brad

03-23-2005, 10:44 PM	#10
tommy knotts Senior Member Join Date: Dec 2004 Location: tunnelton WV Posts: 325	yes leave disconnected,cross A&C,leave original module in dist



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