1981 K10 Suburban ECM questions

[scenic760]

Hey All,

Trying to get everything hooked up to fire this thing up and break it in but trying to figure out what exactly needs to be hooked up since I ditched the carb and installed an MSD Atomic EFI, also the 6AL box, distributor and coil which are all CARB approved... In the process of doing that, I ran across some threads and schematics suggesting that maybe this had some sort of ECM or spark control box/wiring at some point.

In previous post I have noticed that 1981 was a weird year for emission stuff and in that California cars, different engines, vehicle weight, build dates, etc.. would give you different results...to complicate it even further I've also read somewhere that Suburbans were different than trucks?!?!

The engine compartment sticker has it as a California Emissions model...however there does not appear to be any mention of n ECM or spark control on the diagram..that and there is no harness on the firewall, I took a look under the glovebox and there is no module or space for one that I can see....

Alll that being said, I have a connector I don't know where it goes and one of the wires is broken...so I have a three part question I guess:

1. Anyone know what connector that is and what the three wires are?

2. Is it possible I have an 1981 Suburban with no electronic module or more likely the previous owner did a fairly complete job of ripping everything out?

3. Looking at the emissions label, the year part of course is worn off! But there is a part number in the lower left..is that the sticker part number? If I had to fill in the blanks I would say it says it says "model year 1981 new medium-duty vehicles"?

The only issue I'm concerned about is passing smog...THANKS!

 

[Tank6x2]

@HotRodPC thoughts

 

[Blackbeard44]

as far as a module, Im thinking the only module in a 1981 would be an Ignition control module, and thats inside of the distributor, jus a guess but that connector kinda looks like a oil pressure sending unit connector

 

[scenic760]

as far as a module, Im thinking the only module in a 1981 would be an Ignition control module, and thats inside of the distributor, jus a guess but that connector kinda looks like a oil pressure sending unit connector

Thanks!

I think your correct..it looks like only the 5.0L got the ECM for 1981... I'm just hooking stuff up as completely as I can to get it started and break in the camshaft and then will start troubleshooting any issues once it's on the road...

 

[Bextreme04]

What you are thinking of is the ESC that was only on the 305. It used a knock sensor to pull timing when necessary on the 305. The connector in your hand is for the High idle solenoid that is supposed to kick on and put the idle up when the AC is activated. The other side of that wire should be going to the AC compressor clutch and it activates the clutch and solenoid at the same time. You won't need any of that with the Atomic EFI, but you might have an input on the MSD ECU for that signal so it knows to kick the RPM up when the compressor engages. You will also probably need to fix that wiring to remove the connector so that you can engage the compressor as well.

 

[scenic760]

What you are thinking of is the ESC that was only on the 305. It used a knock sensor to pull timing when necessary on the 305. The connector in your hand is for the High idle solenoid that is supposed to kick on and put the idle up when the AC is activated. The other side of that wire should be going to the AC compressor clutch and it activates the clutch and solenoid at the same time. You won't need any of that with the Atomic EFI, but you might have an input on the MSD ECU for that signal so it knows to kick the RPM up when the compressor engages. You will also probably need to fix that wiring to remove the connector so that you can engage the compressor as well.

Thank you sir!

You are correct that the Atomic has a kick up provision..and your also correct as I started tracking the wires that it looks like the wire going to the compressor clutch from that connector has been spliced more than once, some repair is in order...I was pulling on it and it disconnected at a shoddy crimped connector back by the firewall!

I couldn't find a wiring diagram to show the idle solenoid/AC route but I think the AC sends 12 volts to activate the solenoid when the AC get turned on? It looks like the Atomic is just looing for the same 12 volts to kick up the idle? I think I can just zip tie that whole connector and wiring against the firewall disconnected?

 

[Bextreme04]

Thank you sir!

You are correct that the Atomic has a kick up provision..and your also correct as I started tracking the wires that it looks like the wire going to the compressor clutch from that connector has been spliced more than once, some repair is in order...I was pulling on it and it disconnected at a shoddy crimped connector back by the firewall!

I couldn't find a wiring diagram to show the idle solenoid/AC route but I think the AC sends 12 volts to activate the solenoid when the AC get turned on? It looks like the Atomic is just looing for the same 12 volts to kick up the idle? I think I can just zip tie that whole connector and wiring against the firewall disconnected?

If you don't have functional AC, then you dont need any of that. If you have functional AC, I would fix that wire and connect it to the AC clutch. A simple wire tap will let you take that signal to the Atomic ECU for the automatic idle kick up function.

 

[fast 99]

he connector in your hand is for the High idle solenoid that is supposed to kick on and put the idle up when the AC is activated. The other side of that wire should be going to the AC compressor clutch and it activates the clutch

Are you sure about that? It appears similar to the connector that attaches to the oil switch on back of the motor that sends power to the choke thermostat.

 

[Bextreme04]

Are you sure about that? It appears similar to the connector that attaches to the oil switch on back of the motor that sends power to the choke thermostat.

No, I'm not sure... but I believe an 81 would have been a hot air choke from the factory, not electric.

 

[fast 99]

Just thought I would ask. My 81 K20 350 has an electric choke and used the oil sensor for power. Looked very similar.