car is a 93 base model. Recently got the car back on the road following a number of mods including a Twinpower, single turbo, and relocating the relay box to over near the battery. I have the online available '94 wiring diagrams and have been using those to troubleshoot. The issue is that when the ignition is moved to the ON position the dash and parking lights come on momentarily without the light switch being turned on, then go off. When the car is started, those lights come on and stay on until rpms exceed about 2800. At that point they go off until rpms drop below that range. So far I have checked the tns relay terminals - the switched wire that goes to the dash combination switch is not grounding when the switch is turned on. I do not have continuity from that wire to any wire in X-07 where it is supposed to connect with the combination switch. I have double checked continuity in the harness extension I made for the relay box. I can give more details of how I have disconnected every connector under the dash and around the car trying to isolate a short, but that would take forever. What could this be, any similar issues out there?

 

I know this sounds bizarre, but doesn't the air pump come on at around 2800? Check out pg 124 and 143 of the fuel & emission control system schematic. Is it possible that the dash & parking lights got wired by mistake to the air pump's power.

A check might be to pull the A/C fuse (since it powers the air pump) and see if your lighting stays on or off.

 

Thanks for the tip. I've pulled the AC fuses are out, same issue. Additional note - I'm pretty sure its a short because even with the TNS relay out (so lights don't come on) the battery gets real hot when the ignition switch is on for long. any othe ideas?

 

The air pump is on from idle to 3k, you seem to have it backwards.

 

Whoa,
You're right.

Replace " comes on" with "goes off". Regardless, my thinking was that his dash lights were on when the A/P was, and could they have been mistakenly wired up that way.

Later,
J