FRS 4.8 LS swap

[ZDan]

Originally Posted by Zer0

I know for the magnum xl the transmission builder said to use MTF for the transmission. Not sure if gm recommends the same for that transmission.

Should be ATF, not MTF. Dexron III is what Tremec says to use, but many use Dexron IV as well. I have Redline Dex IV in mine.

[kurty85]

Trying to figure out the starter wiring right now. It should not be difficult but it is driving me mad. I hooked up pin 27 from the ecm a33 to the red wire on my harness that is for on and cranking. Then I used the frs solenoid wire left over to the solenoid on the starter and used a direct wire from the battery to the starter post. Everytime I try to crank, the radio shuts off and everything resets. Tried the ls starter and the frs starter, same. Tried different plugs on pin for a good connection, same. when I use jumper cables, both starters spin and solenoids are good. Clutch pedal is in also.

[all4spl]

Sounds like some type of short.

[kurty85]

Been trying everything. Two different starters, using all the frs body wires to crank the starter, checking fuses, nothing changes the "brownout". I have both leads from the harness connected to the starter terminal as well as a cable directly from the battery. Wondering if a33 pin 27 is not a key on cranking supply? Where did anyone else with an aftermarket harness connect the key and cranking wire from the fuse block?

[DustinS]

A33 Pin 27 is not a starter wire. It is the ECU power wire that go live when the ignition switch is turned on. I'm going to go through my wiring and find what I used, but don't use the A33 pin 27 anymore. Surprised you haven't fried anything.



That is the thick white/blue wire used to trigger the starter. That is directly attached to the ignition switch (well sorta). You don't need to do anything other than plug it on to the starter solenoid.

If you are looking for "Switch Power" for you harness. You can use that grey wire to power a relay as the trigger wire.

Okay, Found my ignition source wire. I am going to run a relay (possibly Fan relay 2 that I removed earlier) to power the Ignition source for GM harness. Using the Grey C/Open relay trigger wires (IG2) to trigger ignition relay.

If you follow the Grey wire that comes from IG2 and C/Open relay it leads to the ECM ignition switch wire (from what I understand that is what it is on the ECM). This is the end of wiring for my swap until the MRS Device arrives.

Edit: Hoping this didn't come across as harsh, just not wanting you to hurt anything.

[kurty85]

Thank you very much. I was mistaking pin 27 for being a cranking wire. Opening the fuse box to look now.

[DustinS]

If you are just needing to trip the starter just use the factory wire. White with Blue tracer. if you need switched power to the ECU, use can use that grey wire in the fuse box to trigger a relay to get battery power to the ecu

[kurty85]

Think I got a little further but with weird results. The battery is sitting at 12.29V with nothing hooked up. I checked all the grounds and found 3 grounds disconnected. When I tried to put the positive on the battery terminal, it immediately tried to click the solenoid and roll the starter with the key off. Think the battery is definitely having issues. Also, does there need to be a relay in the ecu trigger wire from the fuse box? Do the two fusible links from the harness both need to be on the starter as well as power directly from the battery?

[kurty85]

Something doesn't seem right here. The psi harness I have says to connect the two ring terminals at the starter. It says they should provide all power to the harness as well as having a heavy gauge wire from the battery to the starter. The red wire that I need to find a connection for is for "key on and cranking". I don't think the gray wire is going to accomplish that.

[kurty85]

Did more troubleshooting today. Have power coming from the clutch switch to the starter relay. Fuse for starter 7.5A is good, just have no power at blue and white wire when cranking.

[kurty85]

Well it was the ecu after all. Just put a plain wire from the starter solenoid to the red and black off the ignition and everything works fine. Going to run that wire for right now and hopefully fix the ecu later. The ecu is locked out and not allowing the signal to crank. And all the flashing of the radio and lights are gone too. Battery was tested good and sits at 12.9 with no load. 875 cca cranks the engine over easily. Now I can get going on the exhaust and get to driving this thing.

[all4spl]

Congrats man! I was wondering what was happening as we haven't seen pictures lately lol. I love pictures.

[kurty85]

It ran this morning!!! Wife actually started it for the first time while I checked for leaks. Fixed a grounded fuel pump on the fuel pump hat, 3 fuel leaks from the FPR, 2 blown fuel pump fuses, and 1 leak from the fuel filter. No more leaks now. The aeromotive fuel pump inlet snapped off so I used my FBM 270 pump. Will post video later today...

[all4spl]

updates! haha