94 Silverado swap questions

[woomugen]

Hi guys,
I have a 94 Silverado I'm putting a aluminum LS1 into and I have a few question about the gauges. I have removed the old TBI harness that goes threw the passenger side firewall (witch also went over to the driver side). Brought it in the house to stay warm while I chase the wires down. My question is what all do I need to keep and what all can I eliminate? I am just trying to keep all my dash gauges working like normal. Do I need everything to run threw the drac unit? I'm using a PSI standalone harness and planning to install the computer under my dash For feeding the beast I have opted to use a ep381 and the corvette filter. I'm going to be using AN-6 fittings.

[Jeebalow]

Speedo, tach, SES or MIL signals come from the new PCM just cut the old ones and splice in the new ones to your gauges (at least that's how it worked on my 95). Engine coolant you can re thread your stock sensor to match the LS head and just thread it into the passenger side head (that's what I did) or you can use the 3 wire camaro sensor and use one wire for PCM and the other for your gauges, I read that this was off so I used the 95 sensor. Oil sensor, buy an adapter and use the 95 oil pressure sender. I didn't touch anything for voltage gauge or fuel gauge.

Also, I completely got rid of the drac unit and the old ECM. The LS PCM was tuned to give the correct 4000 PPM signal for the speed to read which means the cruise control module will be getting the same signal as before as well and should work.

lt1swap.com for the new PCM and alldatadiy are where I got my wiring info.

[woomugen]

Ty. I have already pulled my TBI harness going threw the passenger side firewall. Should I just throw it to the side (other than cruse control circuit, wipper, and abs plug)?

[Jeebalow]

I would double check what the wiring is for in your truck. After 94 they made changes I believe every year. That is why I used alldatadiy to get the wiring diagrams. I am almost certain your wiring and mine are different.

[Mickeymotormount]

I just left most of the old wires in. The voltmeter, oil pressure and temp wires were left in and the original sensors used with adapters to fit the LS block. Speedometer and tach wires were fed through the firewall at the driver's side right to the new PCM.I also left in the old PCM. Rather than try to remove it to make room for the new PCM, I installed the PCM under the hood on the driver's side.

[Bear]

When I did my 94 swap, I removed every wire from under the hood because I was told nothing would be needed. It has been a year since I completed the swap and I have to fix dumb little things because I removed all the wires. As far as connecting your wires for your gauges, 3 will be thru the factory C100 on the driver's side. On the driver's c100 on have the temp wire which is dark green. The alternator wire is brown. And the oil pressure wire is tan.Behind the glove box there is the large black and blue connector. This has your TAC and SES. Also there is a white connector that plugged into to DRAC. The last two wires on one side of this connector are a blue wire with a black stripe and a red wire with a black stripe. Pull the two wires from the connector and wire them together to your VSS wire from the LS PCM. I removed the DRAC and threw it in the trash because I was told I did not need it, and all my gauges work except my temp. My gauge reads 260 after the truck warms up but my live data from the OBD2 says around 170, I noticed on the factory wiring diagram that the supply signal is supposed to be 5 volts and I may have more or a faulty sending unit. I used a meter and checked all the wires from my pin out behind the instrument cluster and to the connector behind the glove box and labeled my wires. I left the pigtail that runs towards the instruments together, but I cut the wires on the mating side so I could pull the pins and solder the new wires and plug them in into the harness as if factory. I have the diagram at my house and will post it for you when I get off work, I had it in previous post for my build, but photobucket got messed up and the photo is not available.

[Bear]

Found the diagram

[chvy=power]

When I did my 94 swap, I removed every wire from under the hood because I was told nothing would be needed. It has been a year since I completed the swap and I have to fix dumb little things because I removed all the wires. As far as connecting your wires for your gauges, 3 will be thru the factory C100 on the driver's side. On the driver's c100 on have the temp wire which is dark green. The alternator wire is brown. And the oil pressure wire is tan.Behind the glove box there is the large black and blue connector. This has your TAC and SES. Also there is a white connector that plugged into to DRAC. The last two wires on one side of this connector are a blue wire with a black stripe and a red wire with a black stripe. Pull the two wires from the connector and wire them together to your VSS wire from the LS PCM. I removed the DRAC and threw it in the trash because I was told I did not need it, and all my gauges work except my temp. My gauge reads 260 after the truck warms up but my live data from the OBD2 says around 170, I noticed on the factory wiring diagram that the supply signal is supposed to be 5 volts and I may have more or a faulty sending unit. I used a meter and checked all the wires from my pin out behind the instrument cluster and to the connector behind the glove box and labeled my wires. I left the pigtail that runs towards the instruments together, but I cut the wires on the mating side so I could pull the pins and solder the new wires and plug them in into the harness as if factory. I have the diagram at my house and will post it for you when I get off work, I had it in previous post for my build, but photobucket got messed up and the photo is not available.

Do you know if the wires on a 95 would be the same?

[Jeebalow]

Do you know if the wires on a 95 would be the same?

This is from my post above, I have a 95 and this is what I did. LEt me know if you need pictures or more explanation on something.

Speedo, tach, SES or MIL signals come from the new PCM just cut the old ones and splice in the new ones to your gauges (at least that's how it worked on my 95). Engine coolant you can re thread your stock sensor to match the LS head and just thread it into the passenger side head (that's what I did) or you can use the 3 wire camaro sensor and use one wire for PCM and the other for your gauges, I read that this was off so I used the 95 sensor. Oil sensor, buy an adapter and use the 95 oil pressure sender. I didn't touch anything for voltage gauge or fuel gauge.

Also, I completely got rid of the drac unit and the old ECM. The LS PCM was tuned to give the correct 4000 PPM signal for the speed to read which means the cruise control module will be getting the same signal as before as well and should work.

lt1swap.com for the new PCM and alldatadiy are where I got my wiring info.

[chvy=power]

Awesome...The white tach wire I hooked to goes to the plug on the pass side. Is that right?