Allright somebody around here will know something. I am trying to figure out what kind of carb I have on my 86 Cutlass. It's an LG4 motor and a Canadian car. Carb looks just like a normal non CCC carb, but it has what appears to be the MCS just like the CCC carbs. But nothing else like TPS, or idle solenoid. HEI is normal vacum advance, and TCS uses a vacum switch. I didn't think the car had a computer, but I was under the dash today and found the ALDL connector?

Thanks for any help
Steve

 

The electrical connector on the carb is for the dual-capacity accelerator pump system (Ref. HP Book "Rochester Carburetors" by Doug Roe, pg 64). It is activated by a coolant temperature switch.

The computer, I believe, is used for the torque converter clutch lockup, and possibly the cruise control. At least, I don't know of any other possible function.

Just curious, does your distributor have a 4-wire connector going to the engine harness, separate from the connector that goes to the dist cap? My '84 van has mechanical carb, vac/mech advance dist, and this extra harness that goes to the computer.

 

Just so happens that my car started out as a LG4....mucho changed now.

Five7kid is right about the dual stage accelerator pump. In fact you can just disconnect the harness at the pump and it defaults to full stroke all of the time.

No computer at all in that car. The ADSL connector is there just because GM used the same under dash sub-harness for US and Canadian cars. The other half of the sub-harness that connects to the computer is missing on Canadian cars.

Torque convertor lockup is controlled by the Vacuum switch and a relay on the Drivers side firewall.

Edit: Spelling

 

Hey thanks guys, knew somebody had an idea. I am pretty sure the TCS is completley manual. There is the vacum switch on the fender. My distributor, is normal, one wire hook up HEI.

Now about the harness, this might be better in the TBI forum. Any idea how complete the harness complete is, ie is the one end somewhere under the glove box with the ECM terminal. I guess what I am getting at is if it is at all interchangeable with the in Dash TBI harness for the 747 ECM or are the pinout wire colors completley different? Or is it a CCC Carb only kind of setup?

Thanks
Steve

 

I believe all you'll find is the ADSL connector...no ECM hookup that I ever found at all.

 

Hmmm so where do the wires terminate? My ALDL definetly has wires running somewhere under the dash.

Thanks
Steve

 

Ah...a revelation. Was looking through my " Canadian Service Manual Supplement " to research wiring diagrams and found that our lttle port is not a Computer ALDL at all.

Quote from manual page 7A-3:

Operation of the external controls can be checked at the TCC test point in the ALDL ( see figures 7A-7 and 7A-8 ). The test point checks for 12 volts to verify that the external controls ( ie: fuse, brake swirch, TCC vacuum switch ) are functioning properly.

Mystery solved. So.... competely different under dash harness's on Canadian models. No Computer wiring at all apparently.

Edit: Termination point for the TCC ALDL is right hand side of kick panel near speaker. From the manual it looks like there is only 1 wire ( 12 volt test ) actually connected to this TCC ALDL port. Hope this helps.

 

Everything helps. Thanks
Steve