72 k5 tbi swap

[ta2ed]

im currently in the process of installing a tbi off of a 93 c1500 on my 72 k5, have been reading on here and a few other sites and the wealth of knowledge on here is amazing. But I do still have a few questions. I'm using 7427 ECM. With harness from donor truck.
1 am I able to do without the Drac & wire Vss straight to ecm?
2 I am using cable drive speedo, what Vss from jtr would work for my application?
3 just outside of firewall there is a grey box with what looks like a circuit board inside of it, what the hell does that go to? I can find it in any schematics.
i would post a pic but not quite sure how to do it from phone.
thanks
Frank

[dave w]

1 am I able to do without the Drac & wire Vss straight to ecm?

YES.

2 I am using cable drive speedo, what Vss from jtr would work for my application?

2000 Pulses Per Mile

3 just outside of firewall there is a grey box with what looks like a circuit board inside of it, what the hell does that go to?

I can't help with this one.

dave w

[ta2ed]

Thanks Dave, I know a pic is worth a thousand words, but damn if I can figure out how to get 1 on here lol. I'm gonna try to copy & paste 1 to see if it will work.

[ta2ed]

Well don't reckon that worked lol http://www.gearhead-efi.com/Fuel-Inj...streply&t=3890

[1BadAction]

Looks like something aftermarket, which is probably why you don't see it in schematics. Do you know what circuit it is in?

[ta2ed]

Not right off, but it was in the factory wire harness. This pic was taken after all the wire loom had been stripped off and I had taped what was left with masking tape to try and keep everything together

[dave w]

Well don't reckon that worked lol http://www.gearhead-efi.com/Fuel-Inj...streply&t=3890

It's a factory part. I've seen that part before, maybe a speed buffer, just can't remember at the moment.

dave w

[Fast355]

It's a factory part. I've seen that part before, maybe a speed buffer, just can't remember at the moment.

dave w

Looks like a Hot Fuel module to me. If it is JUNK the thing. They have a tendency to burn up and could catch fire if you don't catch it in time.

[jim_in_dorris]

Hmmm, It looks somewhat like the intermittent wiper motor control circuit I just installed in my wipers.

[bonnieclyde100]

Well don't reckon that worked lol http://www.gearhead-efi.com/Fuel-Inj...streply&t=3890

that has to do with the brake switch and it sends differant voltages to differant areas like to cruise the ecm and abs computer. i just got rid of it because i didnt need it.

[ta2ed]

that has to do with the brake switch and it sends differant voltages to differant areas like to cruise the ecm and abs computer. i just got rid of it because i didnt need it.

bonnieclyde, You hit it on the head,it is purple wire going to e13,its gettin gone TODAY!
Thank you all.

[ta2ed]

Dave,
Is this the vss i need?

Speed Sensor, # 2PRS
The two-pulse square wave unit for all passenger car TBI installations, all computer controlled carbureted engines, and 1985–1989 TPI engines. 7/8–18 thread, .104" square drive.

[dave w]

Dave,
Is this the vss i need?

Speed Sensor, # 2PRS
The two-pulse square wave unit for all passenger car TBI installations, all computer controlled carbureted engines, and 1985–1989 TPI engines. 7/8–18 thread, .104" square drive.

That is the one. http://www.jagsthatrun.com/SpeedSensors_Order.html

dave w

[ta2ed]

Thanks Dave! I have 1 other question.....imagine that! I will be running electric cooling fans, am I able to use the ECM to turn them on and off or do I need to use a seperate temp switch and relay?

[dave w]

Thanks Dave! I have 1 other question.....imagine that! I will be running electric cooling fans, am I able to use the ECM to turn them on and off or do I need to use a seperate temp switch and relay?

The quick answer is yes, once the .bin has been modified with code changes, the '7427 will operate fans. The stock chip will not have the fan code. There is also some wiring that has to be added to the computer connectors.

dave w