Lotus Europa Community

Lotus Europa Forums => Garage => Topic started by: exarkun1178 on Saturday,November 15, 2014, 03:15:44 PM

Title: Logic Box
Post by: exarkun1178 on Saturday,November 15, 2014, 03:15:44 PM
The last hanging chat on my restoration is the logic box.  How hard is the job?  The shop doing the work doesnt really want to do it.  maybe that they are sick of looking at the car?  anyways.  ordered it from Ray today.
Title: Re: Logic Box
Post by: jbcollier on Saturday,November 15, 2014, 10:21:55 PM
It's not "hard" at all: you just hook it up as outlined in the wiring diagram.
Title: Re: Logic Box
Post by: EuropaTC on Saturday,November 15, 2014, 11:52:50 PM
errr, what's a "logic box" ?

Brian

(struggling to find anything like "logic" in a 60s Lotus   :)   )
Title: Re: Logic Box
Post by: ron parola on Monday,November 17, 2014, 03:39:58 PM
"logic box" controls seat belt light or buzzer on federal cars, something that you guys luckily missed out on. Better yet if you had an MGB it had a diode from it's box to the ebrake lever. WHEN not IF the diode  failed (shorted not open) then, with the ignition on, you pulled up on the ebrake the starter would motor along, sometimes starting the car.... guess how I know! Cheers rp
Title: Re: Logic Box
Post by: EuropaTC on Monday,November 17, 2014, 09:58:37 PM
WHEN not IF the diode  failed (shorted not open) then, with the ignition on, you pulled up on the ebrake the starter would motor along, sometimes starting the car.... guess how I know!

Park brake starting the engine   :huh:    in the words of Mr Spock, "that is NOT logical"......   :)

Thanks for the info Ron, it sounds like an excellent opportunity to "add some more lightness".....

Brian
Title: Re: Logic Box
Post by: blasterdad on Tuesday,November 18, 2014, 05:17:32 AM
I've added a lot of "lightness" over the years... Still regret not unhooking the one in my F150 while I replaced the heater core.  :headbanger: Damn thing drives me nuts!
Title: Re: Logic Box
Post by: exarkun1178 on Saturday,November 22, 2014, 01:12:11 PM
Update

Turns out th elogic box was both cheap ($150) and not to bad replacing (~1 hour)  For the first time since 1989 all the lights work!
Title: Re: Logic Box
Post by: BDA on Saturday,November 22, 2014, 04:57:39 PM
That HAS to feel good! Small pain in your wallet and all the lights working! Just don't tell the ghost of Joseph Lucas!
Title: Re: Logic Box
Post by: EuropaTC on Saturday,November 22, 2014, 11:00:21 PM
 ::)   

All the lights working ?

On the same day ? 

On a British car and a Lotus one at that ? 

oh dear, this isn't going to end well my good man.    You're going against Nature and years of tradition now......  is that smoke I can smell ?
 
:)

Brian
Title: Re: Logic Box
Post by: exarkun1178 on Sunday,November 23, 2014, 05:34:54 AM
I agree im likely at the high spot in the cars life. 
Title: Re: Logic Box
Post by: blasterdad on Sunday,November 23, 2014, 05:54:14 AM
Is the "logic box" just for the seat belt system as ron parola stated, or does it do other things as well?...
Title: Re: Logic Box
Post by: exarkun1178 on Sunday,November 23, 2014, 03:20:09 PM
The logic box in the S2 controls the turn signal lights, break lights and running lights.  Unlikely my car has a seat belt sensor. 
Title: Re: Logic Box
Post by: blasterdad on Sunday,November 23, 2014, 06:29:07 PM
The logic box in the S2 controls the turn signal lights, break lights and running lights.  Unlikely my car has a seat belt sensor.

Thanks for the info, havn't tried any of my lights yet, but good to know when I do. ;)
Title: Re: Logic Box
Post by: Roger on Monday,November 24, 2014, 01:14:19 AM
There's a difference between the DB10 relay for brake and indicator lights and the logic box used in late TCS for seat belt, warning etc.
Don't confuse them. I'm pretty sure the S2 doesn't have a logic box, and I built my own DB10 for about $15.
Title: Re: Logic Box
Post by: 4129R on Monday,January 11, 2016, 12:11:10 PM
I am now finishing the wiring for 3755R which conforms to the later circuit diagram, so the starting number of 3924 is incorrect.

Does anyone actually know what the "logic box" is for?

Is it just about 12 open female terminals in a circular connector, or is anything actually plugged in to it, which I am missing.

I just cannot work out how the starter relay ever worked, as according to the wiring diagram, there is no direct connection from the ignition switch in start mode, via the white and red wire, to the starter relay,which triggers the starter solenoid.

Alex in Norfolk, the home of Lotus.
Title: Re: Logic Box
Post by: jbcollier on Monday,January 11, 2016, 04:34:49 PM
For a brief period the US DOT required that new cars be impossible to start unless the seat belts were fastened.  Each seat had a pressure switch to indicate if the seat was occupied and each seatbelt had a sensor to indicate if was latched.  Needless to say, consumers screamed bloody murder and had many interesting suggestions where their representatives in Congress could stick the system.  The DOT quickly rescinded the regulation.

I would recommend bypassing the system.

At the logic box connector, jump the WR wire (white with a red tracer) from the switch to the YK wire (yellow with a pink tracer) to the starter relay.  Disconnect the N wire (brown) at the starter relay and hook a ground wire to that terminal.
Title: Re: Logic Box
Post by: 4129R on Monday,January 11, 2016, 11:23:24 PM
Thanks very much for that explanation.

I came to the same conclusion about the wiring required.

And there was I thinking the Lotus Europa wiring had been designed by Spock.

Illogical.

Live long and prosper !

Alex in Norfolk.