Deleting ECM ???

[DamHoodlum]

So, my truck has been carbureted for over 20 years now, I originally deleted a lot of the TBI wiring then. I’m getting ready to change motors and want to delete the ECM all together if possible

Is there anything else this will effect I may need?
Does the AC get its signal from there?
Does the fuel pump get its power from there?
Can I energize these circuits somewhere else?


I only need HEI wire, speedometer, oil pressure, water temperature, fuel pump, Alternator, Horn, lights, AC, Wipers.
This appears to be powered from the C100 terminal block on the drivers side along with the plug for fuel pump power. I can move fuel pump relay somewhere for fuel pump as well. This is the way I have it now, but it still has some ECM wiring connected, most of it has been deleted.

I don't need any engine management, cruise control, converter lockup, overdrive, anti lock braking, etc....

Anybody did this before?

Sorry for the long post

Any advice/comments

Thanks in advance

You must be registered for see images attach

 

[Supercharged111]

The ECM will have some say in the operation of the AC. What is your current fuel pump setup? I don't think it fed the gauges back then, maybe an RPM signal for the tach? Do you know what all you connected the ECM to on the engine?

 

[AK49BWL]

Actually on the TBI trucks, the ECM didn't have any say in A/C compressor control - the activation signal went from the head to the compressor relay, which went directly to the compressor. There is a line from the A/C relay to the ECM, but its only purpose was to tell the ECM that the A/C is activated. The only thing you'd need to redirect off the ECM is the fuel pump relay trigger - most everything else is already not a part of it. The fuel pump relay trigger is ECM pin A1, a green wire with a white stripe - which you could put on a toggle switch with the other side connected to the Hot in Run, so it'll shut off when you turn the key off. I only recommend the toggle because Idk how good it is for the pump to run when the engine isn't.

 

[Supercharged111]

If I were to wire up an electric fuel pump for a carb, I'd fire the relay with an ignition hot wire that was interrupted by no oil pressure. If starting was an issue, let a start hot wire fire the relay after the oil pressure switch and use a diode so the circuit doesn't backfired. So it sounds like the AC has its own computer, if that's the case it must rely on an RPM signal from either the coil or the ECM?

 

[AK49BWL]

If I were to wire up an electric fuel pump for a carb, I'd fire the relay with an ignition hot wire that was interrupted by no oil pressure. If starting was an issue, let a start hot wire fire the relay after the oil pressure switch and use a diode so the circuit doesn't backfired. So it sounds like the AC has its own computer, if that's the case it must rely on an RPM signal from either the coil or the ECM?

Runs directly off the coil. This is true even for the Vortecs.

 

[Frank Enstein]

A throttle kicker may be necessary when the A/C turns on. Use the trigger signal to fire a universal relay and have the relay power the throttle kicker.

I removed the ECM from Frank with no ill effects. I was concerned that the speedo wouldn't work but it's been fine on my 92 K3500.

 

[AK49BWL]

A throttle kicker may be necessary when the A/C turns on. Use the trigger signal to fire a universal relay and have the relay power the throttle kicker.

I removed the ECM from Frank with no ill effects. I was concerned that the speedo wouldn't work but it's been fine on my 92 K3500.

That's because the speedo is run by the VSS buffer module, which is its own separate unit from 92-95.

 

[Supercharged111]

That's because the speedo is run by the VSS buffer module, which is its own separate unit from 92-95.

Ahh yes, the diesels had them through the whole run too.

 

[DamHoodlum]

The ECM will have some say in the operation of the AC. What is your current fuel pump setup? I don't think it fed the gauges back then, maybe an RPM signal for the tach? Do you know what all you connected the ECM to on the engine?

Mine is a 1989 Model Cheyenne
I currently use the factory wiring for the fuel pump, Looks like I can get power from somewhere else and move the factory relay

I didn't use any ECM controls to the new motor.

I was concerned that there were 2 wires i may need from the ECM, The AC & Fuel Pump

Looks like i can get around that though

I guess we will see when I get it running again

Thanks Supercharged111

 

[DamHoodlum]

A throttle kicker may be necessary when the A/C turns on. Use the trigger signal to fire a universal relay and have the relay power the throttle kicker.

I removed the ECM from Frank with no ill effects. I was concerned that the speedo wouldn't work but it's been fine on my 92 K3500.

EXACTLY what I wanted to hear

Mine is a 1989, Does the Speedometer still works from C100 connector on drivers side firewall.
and the ECM controlled the electronics for the trans?

Thanks Frank Enstein