I recently bought an lt1 -94 engine, but the DLC (ALDL) is not connected. I’ve been looking around on the internet but I can’t find how it should be.

I found a good illustrating picture from shbox.com


I have three cables on my DLC. B, M and A.

A is ground, but I don’t know where B and M should go. Do you guys know where they should be connected?

 

C207 pin E - ALDL B - PCM Blue 20
C207 pin J - ALDL M - PCM Blue 30

Ive tested this on 90-92, 87 and 87 harnesses to reuse the stock 3rd gen OBDI ALDL

If you have a different year, test the pins with a multimeter or simply run a new ALDL. I would not use the OBDII connector with a 94 PCM. It requires a special cable to even have codes pulled

 

Thank you for a good answer

 

So for OBDI there are only three wires to the DLC?

 

I have 4 on mine, Serial Data, two grounds and a 12v constant which is pins 4, 5, 9 and 16 on the OBDII port

 

OBDI cars are easier to reuse the stock connector. The signal inputs are PCM controlled, which are the C207 hookups. All 12v constant, IGN and grounds are already in place

 

Actually, the stock 3rd gen connector doesn't have 12v constant in it, only in the 4th gens with an OBDII connector, but mine is a '95 motor and had the OBDII cable end so that's what I went with, the 12v powers up the serial adapter I have to read the codes and program the PCM instead of having to run a power cable to the cig lighter.

 

So I have a 92 RS and am going to be swapping a 93 LT1. How many wires does my current ALDL have? I have the daignostic request signal wire from the LT1 (C220 Pin C) and the Serial Data wire (C100 pin D) labeled. What will these take place of?