I have just completed the installation of a 5.3/4L60E out of a 2wd 2001 Silverado into a 1966 Beaumont (same as 66 Chevelle except dash, grille and tail light corners).


I did the usual wiring harness stuff (VATS, 02 sensors, EGR, etc), changed power steering pump fitting from metric to US, power steering pulley from 1987 S10, Hooker cast iron manifolds, Holley 302-2 pan. Still using stock air intake with Edelbrock air filter, stock water pump and fan drive, stock motor mount with adapter plate in stock bellhousing location. Changed stock console shift to cable operation with correct detents.


It is running really good, surprising how quick it is. No codes. Maintains 200 degrees water temp. Manual shifting and kick-down works fine.


Have driven it around for about a week and notice a few minor glitches that I have been unable to solve in-spite of searching a lot.


Glitch 1....It starts in all gear positions. Switch on trans is the black one with two plugs.


Glitch 2....Does not seem to drop to idle rpm on coast, at least not right away. Perhaps being in lock up mode until speed gradually drops too low.


Might be that once the neutral safety switch is operational and adjusted for start in P and N only that other small glitches may disappear as the ECU knows where the gear selector is.


I kept the original main harness and the complete trans harness with the usual modifications. I do have one extra wire that I did not know what to do with. It is the TCC wire. I assume that it connects to a brake switch that is normally closed instead of normally open (might have this backwards).


Anyway, why my neutral safety switch is not working is the main mystery at this time.


Thanks for any advice.

 

Did you wire up a starter relay to the NSS on the side of the transmission?

 

you may not have the switch on the transmission if you are looking for it. I didn't have one on mine when I bought the used trans. I used the supplied switch that came with the B&M shifter.

 

I used the stock wiring from the LS to the starter.


The thick purple is connected to the key start position.


The 4L60E is still connected with the stock LS harness from the Silverado.

 

The factory switch and wiring is still on the 4L60E transmission and connected to the harness just like on the Silverado truck.


This switch is more than just a neutral safety switch. It tells the ECU what gear position is selected.

 

OK I read this again and read one of your other posts also.


Looks like I have gone directly from my key start wire directly to the purple wire effectively bypassing the neutral start switch. That would explain.


So now the question is how do I find the wires that go in and out of the neutral safety switch. This would be over by my ECU where I removed unnecessary wires from the harness and marked the ones that I might use some time such as fan 1, fan 2, cruise, etc.


Switch wiring is as follows based on a diagram I found:


a orange/black...............Park Neutral signal
b light green..................Park Neutral position signal
c pink...........................ignition voltage
d black/white.................ground
e purple/white...............starter relay supply voltage
f light green..................backup lamp
g yellow........................park neutral signal


So based on the above my purple wire going to the starter should connect to pin e


But not sure which wire the key start signal should connect to.....a, b, or g ???

 

You need a relay,the transmission switch will not handle the starting current for long.Your stock purple wire from the ignition switch will energize the coil through the transmission switch,the relay contacts will carry the solenoid current.Thought I had a drawing handy,I'm sure someone will put one up for you.

 

You need a relay for it to work, the switch can't handle the amps that the starter wire will draw. So that said, the purple wire FROM the key switch would go to E the purple and white wire, then G the yellow wire would go to terminal 85 on the relay. Then 86 would be grounded, 30 would be constant hot from the battery usually with a 40a fuse, then 87 would go to the start lug of the starter.

 

Thanks for the details. Now I finally understand where I went wrong. I have been just sending the start signal through a relay to the starter solenoid, BUT without the trigger signal going through the neutral switch first.


Thanks for all the replies. I will follow-up with a reply once I have completed the change.

 

As for glitch 2, the stock tuning will maintain a higher than normal idle RPM when coasting. I believe this was done for emmision reasons.

Andrew