I have an 87 gta with tpi and a standard dash. What is the black box between the power brake booster and the wiper motor mounted to the firewall? It has alot of wires coming out of it. One of the wires broke and I didn't notice anything different when I drive. I connected the wire and still didn't notice anything different. What is it? Thanks for your help. yogi428

 

Tiz be your headlight (door) relay module. Part of what makes your lights pop-up/down when you turn them on.

 

That makes sense, I haven't used my headlights for a while so I wouldn't have notice if the doors didn't work. Someone today tried to tell me the box was the pulse control module for the wipers. I noticed the broken wire when I was under the hood checking my fuel pressure. The car seems hesitate when taking off from a stop. The rest of the time it seems to run fine. The pressure guage says 42 pounds of fuel pressure at idle.

 

Delay for the wipers is built into the motor/transmission assy.

42 seems a bit high for a stock fuel pressure. Stock for 87 should be around 37-39 at idle. The extra FP doesn't hurt anything. The FP should rise (and drop sharply) if you snap the throttle (no load) or raise if you're driving. If it's constant, you may have a vac. leak at the regulator.

Adding or removing the vac. line to the regulator should change the FP readings if all is well. The rise in pressure is similar to a carbs accelerator pump (adds extra gas when the throttle is opened).

Just guessing though....