89 mustang 5.0 crazy headlight/dash gauge problem

i physically unwired it, the previous owner said it started doing the problem im having when he put the new headlights in but he did not touch the wireing. he only had the headlight bulbs hooked up because the blinkers and parking lights would have had to be cut and spliced being that they were aftermarket ebay lights. The only thing i noticed was when i put the old headlights back in i noticed the left side blinker had one of the peices of metal burnt out inside. i forget what theyre called. and the bulb you could barely see through it almost looked like it got really hot. i replaced the bulb but its still the same.
 
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i physically unwired it, the previous owner said it started doing the problem im having when he put the new headlights in but he did not touch the wireing. he only had the headlight bulbs hooked up because the blinkers and parking lights would have had to be cut and spliced being that they were aftermarket ebay lights. The only thing i noticed was when i put the old headlights back in i noticed the left side blinker had one of the peices of metal burnt out inside. i forget what theyre called. and the bulb you could barely see through it almost looked like it got really hot. i replaced the bulb but its still the same.

The prong inside the socket. Take the light back out and make sure it didnt melt to the point that it is touching the other one and shorting the circuit

Being that this didnt happen until the PO touched the lights i would really go over everything over there , There is something you missing up there that is the culprit to this. End of story if all was well until he changed them its now the game of tracking what he did up there
 
take a dmm set it on ohms put the red lead from ground in the radio and the black lead on bare metal in the car the reading for a good ground should be 0.1-0.5 ohms , then you know that is not an issue . go through that headlight harness I have a feeling there is something you are missing that he touched up there
 
Bad ground - there are three possibliltes:

1.) Bad engine to body ground - this would cause the temp gauge indication to rise as electrical load increases. The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.

2.) Missing or defective turn signal ground - see G102 & G103 on the drawing below.
turn-signal-grounds-and-engine-comartment-wiring-jpg.64670


3.) Both grounds are missing or defective.
 
thank you very much, i did remove and clean up the two front grounds they are on the radiator mount unless them are different ones, and i will be jumping on the engine body ground asap. thanks for the nice diagram picture.
 
Ok so i hooked up the engine to body mount and the only difference is with the key in the on position the tachometer goes up to about 1200 rpms. i still have the problem with the lights and i double checked the two turn signal grounds.
 
ok key in not on, press trip/reset and hold,turn key to acc on-not starting it, just to 1st clik,leave key there,look at display while holding button, when test displays,let go of button, be quick, next all needles sweep to max - then back to normal,, readout now says gage,, push button once, digits all light, press and it says bulb and lights all bulbs, like batt trac cont. etc.., press and rom ver displays, press shows EE level patr of the ID, press shows hex val for manufacturing test date, press and any diagnostic trouble codes are shown (have pen/paper ready)press and ENG followed by speed mph,press speed in metric,press and tac then tac #s,press and fuel levelpress,oil pressure,press temp,press batt lvl,pressRH codes-a few screens then flash,press cr code H for off vehicle..can do running just start once in test mode DTC CODES-9202 fuel sender open circut..9204 fuel sender short to ground..9213 antitheft key # below min..9232 or a103 no antenna detectit will give obdll codes then pe codes then back to gage EXIT presstripbutton 5 sec reg odometer back 9342 ecu defective 5284 oil press sw fail a141 a143 nvm problems copied from a friends shop flyer.. hope it does someone good
 
ok guys i think i may have a lead on it. i removed the two turn signal grounds under the hood. theres one on each side they are grounded on the top of the radiator support. with the grounds off the headlights shut off and my dash goes dead when i turn the headlight switch on with them on low beam. also the turn signal indicators come on, the exact same problems im haveing with the grounds hooked up and i switch to high beam. Where are the grounds supposed to be hooked they dont look like they should be there from the factory. The grounds im talking about are in the pictures above, it definetly seems like something to do with these grounds