Hey all, A few months ago, My mate bought a TJ which I helped him put the head unit in. Problem is, with the Dimmer switch not being wired in, everything was very dark at night. This he could live with. However, He tells me that one day he stopped, turned the car off for about 20mins, then came back, turned it on, only to notice that he had no lights at all inside the dash.

The gear indicators in the cluster work perfectly during the day with no lights (PRND321), but when the lights are on, PRN light up, but D321 dont. There's no cluster lights at all to light up the speedo/tacho and the Trip computer dims to black when the lights are on. I'm no electrical guru, so I'm asking you guys what the problem could be?

-Ian

so no-one's got any idea?

Sounds like a simple blown fuse!

Anyways, in reference to the head-unit. the dimmer wire will only send a signal to the HU telling it to dim or not, its an *optional* wire.

Another thing it could be is the wires running from the dimmer switch on the right under the cluster, check the wires for damage. the dimmer wire should not affect this at-all. Just make sure its cut clean with no exposed copper or it could tap something and blow a fuse.

Anyways, in reference to the head-unit. the dimmer wire will only send a signal to the HU telling it to dim or not, its an *optional* wire.
Its not optional in all models, plenty of 3rd gens I've seen lose the control over the dimmer lights if you haven't wired the dimmer into the headunit, typically the newer models (I think TH+). I believe (and don't quote me on this) if you earth the dimmer you should be able to control the brightness again.

As to why they don't work, theres combination of possibilities. 1st is a fuse, sounds most obvious like Life pointed out, probably want to check through any relevant fuses. If they're all fine, pull the cluster surround out and check the connections to the dimmer wheel, if its not connected properly, the lights don't work.

Can't comment on the D321 thing, never tried putting the car in gear when I've had the dimmer circuit open.

Its not optional in all models, plenty of 3rd gens I've seen lose the control over the dimmer lights if you haven't wired the dimmer into the headunit, typically the newer models (I think TH+). I believe (and don't quote me on this) if you earth the dimmer you should be able to control the brightness again.

isn't that why the fuse blows cause people use the dimmer as the earth?

Its not optional in all models, plenty of 3rd gens I've seen lose the control over the dimmer lights if you haven't wired the dimmer into the headunit, typically the newer models (I think TH+).

Not the TH, I have the xplod harness hard-wired which doesnt include a dimmer wire and I just snipped it clean so nothing is exposed. Dimmer works fine, no problems at all. HU just stays at full brightness at all times. (June 2000 TH Exec)

i haven't got got my dimmer switch connected in my TJ sports and it still works fine

You'll probably find what it varies by then is the model deck that comes standard in the car. I know some 3rd gens do it, I've seen a few in person and I've heard of plenty through here. I don't think mine was affected when the dimmer wasn't wired.


isn't that why the fuse blows cause people use the dimmer as the earth?
Dimmer as an earth for what? My understanding of it is its one of the earths for that circuit, the dimmer circuit grounds through the headunit, so if you haven't got a dimmer inbuilt in the headunit, I couldn't see why earthing it directly, whether that be to a screw holding the headunit in or somewhere else would have any different affect to it being wired to the deck.

Just bumping this thread to get some more possible scenarios so that I can have look at it during the week. Anyone got any other ideas?

Also, What colour is the dimmer wire in the 3rd gen? I forget as me and my mate stupidly cut the metal loop of the end, now it's just a bit of dangling wire. lol

You need to wire a fresh earth for the head unit straight to the body.. Yes the dash lights and and rear tail lights will have gone out. they are on the same fuse and are the first to blow after a head unit install.. Thats why you wire a fresh earth straight to the body for the head unit..:)


Also if you want a dimmer for the head unit you are proberly better of taking a signal fromn the light in the cig lighter.. leave the dimmer alone.. Thats my thoughts anyway..:)

You need to wire a fresh earth for the head unit straight to the body.. Yes the dash lights and and rear tail lights will have gone out. they are on the same fuse and are the first to blow after a head unit install.. Thats why you wire a fresh earth straight to the body for the head unit..:)

Thanks EGO :D I'll give that a try.

Thanks EGO :D I'll give that a try.


Also where are you getting your power for the head unit from..??? Also where are you taking your trigger from..??

Using the original trigger int he harness is usally good but for power it is always wiser to run a fresh line fromthe battery.. They onle use small wires in most cases in the harness. also depends on the age of the car.. From memory the TJ had a decent size power.

Standard head units dont draw much power but once you change headunit which most these days have min 200watts will push the limits of stadard wiring..