Instrument cluster problem. help?

[chuck4w2000]

hey everyone, i have a 91' 240sx. and when i first start my car when its cold i have no dash lights, speed, or hud. i do have rpm, coolant temp, exe. i searched long and hard to fine something on here but came up short. i did find something about the TCU burning out. i removed it and found no evidence of burning on the board. i have no access to wiring diagrams for the instrument cluster. so any advice on how the dash lights are controlled or other known problems?

[fast240sx240]

After a while does the rest of the dash lights and ect come on or is it permanet?

[chuck4w2000]

yes, after about 25min the dash lights come on and stay on as long as the vehicle is on, it acts like it is temp related, on days where it is hot and sunny there is no problem.

[amolao]

Check your ashtray and glove compartment, and (if auto) your gearshift dial. Do you have lights there?? If yes, then you know you are getting the initial voltage you need to run all your interior/cluster lights. But seems like is getting grounded during cold days by one of your appliances by the time it goes to the cluster/dash/hud....They are two different paths. I would disconnec the HUD and run a test. If the lights work fine then your HUD (behind instrument cluster) is the culprit.

[chuck4w2000]

ok, i do have glove, and cig. lights. i disconected the hud like you said and nothing changed. i supplied it with its own power(dash board lights) and nothing changed. ground side? i would thing that the dash lights would be ground side switched. is it controlled throught the circuit bord in the instrument cluster?

[amolao]

You have straight 12v feeding the ashtray, dash,glove compartment,etc lights.

The 12 going to the cluster,hud,dash,etc are controlled by the TCU. Yes they do use a different set of grounds as well. Something is grounding those 12 volts to ground when the temps are cold. Is a sign of electrical temp failure. If you took your HUD out of the circuit already then start disconnecting other things at a time. It might even be your TCU if all those items are failing at the same time.....get the wiring diagram from the online FSM, it make things easier. Sorry for the long post.