i am having some problems wiring my head unit, i can't get it to get power and everything is wired properly, does anyone know how much power should be at the accessory and lead power? i read with a multimeter that the lead was 12.6 and the accessory was around 3.5? is this correct?

 

Did you buy a harness for it?

Soooo much easier if you didnt

 

wait, ok, did you just suggest that its easier to install if he doesn't buy a harness? thats the most retarded thing i've ever heard..

you should read 12.x volts on accessory and constant, make sure the key is turned on when reading accessory, and check your fuse under the dash, its a 10a fuse, if its blown you will get no voltage from that lead or it will back feed and read some funny voltage.

 

No no haha.

Guess i worded it wrong sir.

I meant its soo much easier to have the harness if he didnt already have it

 

MM&Y of car would help.

As mentioned, with ign. switch on you should get 12.x volts, [around 12.5V and with engine running, around 13.5V] on both the acc. power lead and the constant power lead.

Without suggesting anything, are you using a harness adapter or is the HU harness hardwired to the stock radio harness, [stock radio plug cut off]?

Most Honda/Acura have the radio acc. fuse in the under dash fuse box and the constant power fuse in the engine bay fuse box, the acc. fuse is almost always a 10A and the constant power fuse is a 7.5A.
BTW, if you are using the HUs internal amp, the HUs constant power, [yellow] should be wired directly to the batt. by running a fused 12ga lead from the batt. to behind the HU and connecting the yellow to it.
You should also install a 12ga chassis to chassis ground, if you are using a metal back support from the chassis of the HU to the cars chassis, [stock rear support bracket, dash sub frame]then it will suffice as the chassis to chassis ground. 94

 

yes i am using a harness adaptor, my head unit worked fine before but i recently had my dash out to remove the ac internals and clean everything up, but since i put my dash back in i've lost constant power to my dash clock, and the white/blue wire on the car harness(not sure if that the acc or the lead power?) but it has only 3.6 volts, so i must have pinched something putting my dash back in... i'm taking it all out again right now to inspect it... or is there something else that could be causing this?

 

check connection to clock, on my integra the constant on the clock runs to the same fuse as the constant for the hu, sounds like a simple mistake somewhere, soemthing didn't get plugged back in, bad connection, or as you suggested, pinched/shorted wire.

 

yeah man i just took my dash off and had a look at it, and the white/blue wire makes a "Y" to the HU and the clock so i followed it back and there was no shorts any where, and i tested it at the connector on the fuse box and it still had 3.6 in the on position and 0.00 on the acc position.. so i don't know what to do from here.. any ideas?

 

maybe you forgot to plug a harness back in near the inside fuse holder on the back.

 

take a quick look around and see if anything else is not functioning correctly.

 

i just went and had a look man. and all the connectors on the fuse box are fine, i never had unplugged anything to begin but its all fine, and i had my dash fully installed for about a week before today, and the only thing i noticed that wasn't working correctly was the clock and my head unit

 

just for kicks, check the fuse box under the hood.. 7.5a fuse.

 

I guess we will just have to guess what the MM&Y of the car is, or did I miss it???

As mentioned, and as you now know, the white/blue is a 12V+ constant power for the clock and the HU memory, it is also sometimes used as the ECU/ECM memory and it is, [or should be] hot at all times.

Also as mentioned, in most Honda/Acura it is fused in the engine bay fuse box and a 7.5A is the most common fuse size used for that circuit, test for power at that fuse, [both test tips]. 94

 

ohh sorry man its a 1992 Civic SiR... i just went out now and the fuse is fine, it had 12.30 volts at one tip and the same 3.58 at the other tip?

 

wait... the same fuse.. read 12.30v on one leg and 3.58 on the other? thats a blown fuse right there..

 

ahh yes, i overlooked it last time but it is blown, so i shall replace it, thank you guys very much, i feel dumb, but learned something

 

Replace the fuse but do not use the stock radio harness 12V+ constant for your aftermarket HU, run a fused 12ga lead from the batt. instead, the stock radio constant can not supply the current needed by most "high power" aftermarket HUs, especially if you like to crank up the volume, running a lead from the batt., [along with a chassis to chassis ground] will improve SQ and bass extension. 94

 

not a bad reccomendation at all... imo this depends completely on the end user

for someone who has the extra time/know-how, or the extra money to get it installed... this is a good idea (if they like to listen to their stereo at high volumes)

if this is for your average grandpa who will never get the volume past level 10 i dont think it is necessary