Need crank wire after removing tbi computer and harness

[Techson94]

Need a hand here. 1989 k3500. Removed 454 tbi computer and harness for 6.0ls and fitech ultimate ls system.

They old start wire to the starter does not have power on crank. I can't find any wire that powers in start position.

Any ideas on how I can find start power to send to fitech?

 

[Bent77]

On the original system there was a purple/wht wire that drove the signal to the ECM that it was cranking
This was interrupted by the neutral safety switch

87-91 TBI wiring Diagrams

TBI wiring diagrams for 1987 to 1991 C/K/V/R trucks. 1 to 5

ck5.com

 

[Techson94]

Thank you. Makes sense. What is right way to correct this? Bypassing neutral safety doesn't seem like right thing to do.

Do I need to rewire the neutral safety switch?

 

[Bent77]

I think what I did was steal voltage off the solenoid trigger, used that to trip a relay and send clean power from the relay to the computer for the crank signal

 

[sweetk30]

fuse block under driver dash has key hot and key & crank hot tap points . can just use one of them with relay and feed that from battery .

 

[Bent77]

fuse block under driver dash has key hot and key & crank hot tap points . can just use one of them with relay and feed that from battery .

His does. Mine don’t

 

[Techson94]

IThank you. Makes sense. What is right way to correct this? Bypassing neutral safety doesn't seem like right thing to do.

Do I need to rewire the neutral safety switc

His does. Mine

 

[Techson94]

Bent 77. Can you clarify what you meant when you said pull power from solenoid? Understand relay then to starter.

 

[Bent77]

Bent 77. Can you clarify what you meant when you said pull power from solenoid? Understand relay then to starter.

I intercepted the signal wire that triggers the start solenoid.
As was mentioned by @sweetk30 above, you likely have that open at the fuse terminal block for your model year to be able to pull from there

 

[Techson94]

I've tested every circuit in fuse panel. It either has constant power or shuts off when cranking

 

[Bent77]

Mine is just another wire to the coil for the solenoid, back up to the signal needed for the ECM.

Hot while cranking
Then Ignition hot constant
Main feed power off the battery

 

[sweetk30]

I've tested every circuit in fuse panel. It either has constant power or shuts off when cranking

the extra single pin sockets not a full fused circuit . if i recall top of the block .

 

[Techson94]

I thought I was losing my mind. When removing tbi computer I cut out 1 to many wires. 2 power leads on fuse block. I cut one so fuse block had power to most but not to crank signal. Once I fixed that. Crank wire triggered. 2 days on that one. Thanks all.

 

[1-ton]

1989 k3500

Not to be too picky here, but your truck is a V3500 and not a K3500. I should know...I own one. Make sure you say V3500 to the parts counter guy or gal, or you could end up with the wrong parts. Hell, even if you tell the correct info you could still end up with the wrong parts...such is the life of a Chevy V/R series truck owner.