1989 toyota supra
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=12119
Printed Date: May 15, 2025 at 3:22 AM
Topic: 1989 toyota supra
Posted By: primo_civic
Subject: 1989 toyota supra
Date Posted: April 12, 2003 at 3:35 PM
im currently hooking up a JVC deck to my friends 1989 supra. i checked out the wiring diagram under the 12 volt archive and followed both that and the wiring instructions that came with the deck. now, everything is wired up but there's 4 wires that aren't connected.....antenna trigger(no power antenna), illumunation, a mystery WHITE/ green wire ( not shown in the 12volt wiring diagram) and another wire i assume is for the dimmer. the deck won't power up at all....and there is power from the constant 12v.....any ideas?
Replies:
Posted By: esmith69
Date Posted: April 12, 2003 at 4:50 PM
Check to make sure the deck is also properly connected to the switched +12 volt wire ("accessory"), and that there is voltage going through this wire when the key is in the "acc" and "on" position. If you get no voltage, then I'd say check the fuses throughout the vehicle--I'd recommend using the continuity function of a multimeter to verify if a fuse is good, cuz many times even if it looks okay it can still be blown. You should check all the fuses even if they don't say "radio" on them cuz a lot of times they are mislabeled, and besides wouldn't you want to know if you had a blown fuse in your car? And while you're at it check the fuse that's in the back of the radio The three connections that are absolutely necessary for the deck to just power on, are switched and constant +12 volts, and a good ground. An easy way to check for a good ground is to temporarily run a wire from the constant 12 volts to the switched 12 volt wire in the back of the JVC, because you already know the constant wire is good. The radio should DEFINITELY power on, and if it doesn't you know you need to find a good ground, or the radio is messed up (very unlikely). This WHITE/ green wire you're talking about...is that a wire that's part of the JVC's harness? or is it part of the vehicle's wiring?
Posted By: Velocity Motors
Date Posted: April 13, 2003 at 8:03 AM
Make sure that you have a solid ground wire. I tend to steer away from any OEM grounds as they are not very reliable. Find another source for ground and post your results.
-------------
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA
Posted By: primo_civic
Date Posted: April 13, 2003 at 10:07 AM
esmith69 wrote:
This WHITE/ green wire you're talking about...is that a wire that's part of the JVC's harness? or is it part of the vehicle's wiring?
The fuse has been replaced and there hasn't been any change. The White and Green wire is part of the OEM harness. All of the wires used in the JVC harness have been used except for the Antenna wire.
Posted By: bberman1
Date Posted: April 13, 2003 at 10:33 AM
You need to get a voltage meter and test your +12 volt switched wire. You should get + 12volts when the ignition is on and no voltage when it is off. Also double check your constant and make sure it has +12 volt power with the ignition on and off. And also use the continuity function on your voltage tester and make sure you have a good ground. This will let you know if the head unit is getting the power it needs. And if there is a problem it will let you know where the problem is coming from. Post your results!
Posted By: primo_civic
Date Posted: April 13, 2003 at 11:03 AM
alright, so i check all the fuse and they are all fine. got a multi-meter and checked the constant 12V and its giving me pretty much nothing. what's weird is that i went back and hooked up the OEM radio and its working fine. I know the JVC deck is working fine. I grounded it before i started connecting the other wires. Im thinking of getting my friends 12V power supply just to make sure that the deck is working. If it is, is there any other reason why it wouldn't work?
Posted By: bberman1
Date Posted: April 13, 2003 at 11:28 AM
If you have no power on the constant wire the head will not turn on the constant is what supplies the head with power. What color is your constant that you are taping into? Also did you test to see if you get a switched 12volt?
Posted By: primo_civic
Date Posted: April 13, 2003 at 8:24 PM
i tested the constant 12V using a Light tester. the constant 12V on the supra is Blue and Yellow. its only reading 1.84V . I tested the Switched 12 and that works as well. One thing i think i should mention, there's two radio plugs that plug into the back of the deck, one smaller than the other. any ideas on what could be?
Posted By: esmith69
Date Posted: April 13, 2003 at 8:55 PM
Were they plugged in to the factory radio? Or do they look like they would plug in to these? If so, those ARE the plugs/wires you're supposed to use to hook up an aftermarket deck. The normal (and highly recommended) method is to use an adapter like the Metra 70-1761 that just plugs in to those factory connectors. Then the bare wire ends of your JVC harness will hook up to the bare wire ends of the Metra harness (just match color to color except for the orange ones--match function to function for those).
Posted By: primo_civic
Date Posted: April 13, 2003 at 9:49 PM
i know what you're talking about but that's not it.....im not talking about the harness itself.....im talking about antenna plugs...i have to of them, one smaller than the other...sorry for the general statement.
Posted By: esmith69
Date Posted: April 13, 2003 at 10:04 PM
What do the plugs look like? Does one of them look like a DIN plug? And maybe the other one like a standard motorola end antenna? The din plugs are usually for cd changers, external factory tape/cd players, and occasionally, factory amplifiers. The other one is, well, the antenna cable. I have yet to see a toyota with two antenna wires (like the nissan diversity antenna systems), so I doubt both plugs are for the antenna. Check out these toyota diagrams--do any of them look like the back of your factory radio? or do any of the plugs look like they'd plug in to any of these toyota radios?
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