has to cool down before restarts

where is the diagnostic plug on a 1990 plymouth voyager?
is it inside the engine or under the dash?

my email is

Where is the body control computer located? Is there any other computer modules on this van and where are they located?

I noticed my breaks on my van were getting loose. Then one day they went out. I mean pedal all the way to the floor and nothing. There was no break fluid in there so I had some put in, still nothing. I had the breaks bled all way around, still nothing. I then had a naster cylinder put on and still nothing. I don't know what's wrong...

Tried checking the o2 sensor, fuel pump, fuel filter, fuel injections system, did an oil change.

'89 3.0 engine,repairthecoolanttuberuns through the block

how to replace a fuel on the van taking it a part and putting it back together.. thank you