Elec problems...experts help needed

[88stangmangt]

ok here is the problem im hopeing some one will help that messes with them more than me...my headlights dont work...only do they come on when i turn the key all the way over to engage the starter...cant figure that one out my runners stay on all the time in the rear...i have already completly disconnected the head light switch on the dash...i cant find a GOOD in depth diagram of the headlight system....car is a 90lx 2.3 everything was working great before i pulled the motor. im trying to get this sucker back to the dyno although headlights wont stop me im still needing it fixed to pass insp...now other question is sensors on the lower manifold them selfs one is air intake temp??? and the other??? also which wire runs to the temp sender on the side of the block???any help would be awesome..

 

[goland55]

Headlight problem:

Do you have a multimeter or ohmmeter? If so I would ohm out the wires from the headlight switch to see where they're going. I'm thinking that there's something up with the wiring on the steering column or maybe someone hacked with the wiring at one time and connected the headlights to the starter solenoid (or similar) and now possibly you've got the wire on the other side of the solenoid so it's only hot when you turn the engine over instead of being hot all the time. Those are just guesses...you won't know what's wrong until you get in there and start tracing the wires... an ohm meter will help a lot.

Lower intake sensors:
On a 90 you should have the ACT (Air Charge Temp) sensor towards the firewall side of the lower intake, the fan motor switch screwed in from the driver's side, and the coolant temp sensor screwed in from the top between the intake runners.

I dunno what wire you're talking about...try tracing it out with an ohm meter when the car is off.

 

[88stangmangt]

well i am a mechanic and the hobby shop manual i have states the 2 brown wires are supose to get hot when you press the switch once for the running lights but those are constant hot...so somewhere i have a back feed...untill i can find a good diagram...my lower intake only has 2 sensors on it one in the back toward the firewall and one between the INJ's...i broke the one at the inj's when i was puting my 75lb injs in....there is a 2.3stang at the JY i can look to see what wire goes into the temp sender in the block.

 

[goland55]

Are your taillight/parking lights always on as these two brown wires are hot?

My chiltons shows a tan/white wire feeding through the headlight switch to a brown wire and then to the tailight/parking lights. If both of those are hot, the tailight/parking lights should be on....unless the chilton's has the colors wrong and you're talking about different wires.

 

[88stangmangt]

my lights are always on and these wires are always hot..

 

[goland55]

First thing I would suggest is pulling out the taillight/parking light fuse. If the lights go out, that means the headlight switch is toast and is staying on all the time. If the lights stay on then that means they're most likely getting fed through the brakelight switch, hazard switch, or the multifunction switch on the steering column.

I would then try unplugging the multifunction switch on the column. If the lights go out, that's the culprit...if not, repeat with the other two switches.

If unplugging all three switches doesn't turn the lights off then I would verify that your ground near the lights ohms out with the negative side of the battery.

If none of that points to the problem then you may have something funky going on with your wiring.

 

[88stangmangt]

i found the problem...we had a harness plugged in wrong....now all ligts work as should....thanks for the help..

 

[goland55]

No prob. Just curious, which harness was it?

 

[88stangmangt]

it was the main harness that controlls the headlights and runner...not sure what harness it was in that it wasnt supose to be because my buddy found the correct plug while i was searching under the dash...this also cured the problem or the tail staying on and my fuel pump geting no power.....we had it on a toggle switch at the relay....took that out and put the relay back in and back fuel pump primes with key in acc.....i got the coolant switch on the top on the intake plugged in its a 2 wire switch...but do not know what the other one is in the back of the lower intake....id assume its air temp sender...but my manual said nothing about it its a one wire sender..as well as the one in the side of the block that i believe runs the stock temp guage with i dont need i have a autometer...any ideas??