I have already de-pinned the harness(as per lt1swap.com), im just wondering if ill need to make up an obdii connection etc, specifically for this swap. It seems that the site is more so geared towards installing the engine in a vehicle that isnt already equipped with a computer etc. An example would be which computer should i have running the fuel pump?(Does it matter?) which should have the Alternator connection?
Last edited by shmiet; 03-10-2013 at 03:37 AM.
I am certainly no expert on this, but will the 98 fuel pump handle the required pressure of the later engine? You may have to run the later pump, which would mean running that off the later computer. I think you will need the obd11 wired to suit the newer engine also, as you will be reading codes from the new engine.
1978 C20 short bed pickup, GEN111, 4L60E trans.
The '98 fuel pump is more than up to the task for a stock engine. The fuel pump relay can also be used but must get it's actuating power from the new PCM. I found this out by mistake. I used my existing relay/computer and when I started the engine, it died in about 10 seconds. Turns out, the old PCM would power the relay and the system would prime for start. After it started, the old computer powering the relay didn't "see" any information coming from the engine(crank signal, rpm, etc), so it would de-engergize the relay. I simply used the fuel pump relay wire from the new PCM to energize the existing relay. It worked like a charm.
Your new PCM should power the alternator, but I would retain the existing battery idiot light wire(if equipped).
As for keeping things simple as possible, you need to power the new PCM. You will also need to get it flashed to remove the VATS(Vehicle Anti Theft System).
You need to retain all your wires for the instruments(oil pressure, voltage, rpm, water temp,).
As for soldering connections, there will be some of that required. I don't rely on crimped and taped connections on something that I will be driving. Nothing is worse that being stranded somewhere due to a loose connection. Solder them and shrink wrap them.
Not sure if you can use the LS type compressor in these trucks. I read something about it and it requires frame notching.
Since you already have an OBDII system, only one wire is required to run to the new PCM. This way you can read any codes that may pop up.
Last edited by Mickeymotormount; 03-10-2013 at 07:26 AM.
'93 Chevy 1500 4X4 ECLB with a '99 Silverado LQ4 6.0 and '99 Escalade 4L60E. SOLD IT!!
New toy: 2001 2500 HD 4X4 Extended Cab Long Bed
John
Right on man, thanks alot. I will be using an aftermarket fuel pump, not quite a stock engine haha. I will solder i just didnt want to redo all the connections thats why im using both ecus.
-Would that single wire for the obdII allow for reflshing of the Ecu? Happen to know which wire?
-will i need to get the old ecu flashed at all? or am i good to just rip the unused wires out of the old harness?
Last edited by shmiet; 03-10-2013 at 12:47 PM.
By using the original fuel pump relay, alot of your wiring is already in place. Simply remove the actuating wire coming from the old PCM(ECU), and attach the fuel pump relay wire from the new PCM in it's place.
Reflashing of the computer requires special software. Not sure what's involved, but I sent mine to Brendan Patton on LT1swap.com. Turnaround time was about 1-1/2 weeks. He'll need to know everything about your truck, from tire size to transmission used to gear ratio. He can also program to actuate electric fans if the original donor vehicle did not have them. Cost was $75 and shipping to him. His shipping is included with the cost.
http://lt1swap.com/programming.htm
Nelson also provides these services and can also modify the programming for engine modifications. Since my engine is stock, I did not need any additional programming.
The single wire for the OBDII is only to read codes that may come up.
Reflashing of the old PCM is not required. I don't think the the old PCM is required at all. I still have mine but it is not used for any of the functions of vehicle running or driving.
The PCM wire for OBDII may depend on what year harness/engine you're using.
http://lt1swap.com/wiringharness.htm
Last edited by Mickeymotormount; 03-10-2013 at 03:05 PM.
'93 Chevy 1500 4X4 ECLB with a '99 Silverado LQ4 6.0 and '99 Escalade 4L60E. SOLD IT!!
New toy: 2001 2500 HD 4X4 Extended Cab Long Bed
John
Thanks again man, you just saved me a bunch of time.
Make your truck simple,get rid of the old black box,the 411 PCM will run everything in your 98 with the correct re -pin and reflash.
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