I am installing a new cd player in a 1992 740 wagon (non turbo). I took the old tape player out and found out a few things: the previous owner had wired the white rheostat wire in with the two yellow w/ white stripe wires, this was causing the lights to not turn off. For the longest time I thought it was either a bad switch or relay, and after changing both of those, I had no luck with the lights. I then thought it was a grounding issue, so I ran a new ground wire from the relay. Still no luck. Once I removed the white rheostat wire, the head lights worked fine again.

However, my question is about the green/red striped wired. The wiring diagram I found on the internet tells me that this is the 12v constant supply to the CD player. However, when I check this wire with my digital multimeter, it only has 3v. This is both when the car is off, and when it is running. So, when I have the cd player hooked up, it won't power on. The 12v ACC wire is getting power, and right now I have both of the CD power wires hooked up to that. It works, but it's annoying because it won't save any of the presents (radio station, CD track, etc.)

Does anyone have any tips or advice?

I also currently only have the two front crossover (dash speakers) and front door speakers hooked up. I was thinking about removing the amp and hooking up the rear speakers as well. Would it be a good idea to just splice in a wire from the old amp harness wire to the 12v constant on the cd player?

 

this si the wiring on my 1992 740 wagon. note that colors NOT in () are the standard jap aftermarket stereo wire colors, and colors in () are the Volvo harness colors.

https://docs.google.com/document/d/1...it?usp=sharing

note also, this is a little more complicated, because I put component speakers with seperate tweeters in the front, I put the tweeters in the dashboard mounting spots (my dash speakers were toast, so i removed the cones and magnets, and glued my tweeters in there using a bit of RTV. I put my component speaker woofers in the front door positions, and I put some regular 2-way speakers in the rear doors.

I most certainly bypassed the amplifier... a modern '50wx4' stereo has more juice than that 20 year old amp.

 

That's actually the diagram I was using. My trouble is with trouble shooting why the 12v constant isn't getting juice. Any ideas?

 

my notes say its from fuse 5. let me dig up the vehicle wiring diagram again and double-check.

yeah, my 1992 greenbook shows the exact same thing... green-red on connector D pin 9 comes from fuse 5, which in turn gets power directly from the 'positive terminal' (over behind the driver-side dashboard jammed up against the firewall). fuse 5 also powers the antenna.

I note that 1991 & 1993 is the same (at least on these wires, didn't check *everything*) but 1994 940s' are somewhat different.

 

Hey Pierce,

It was fuse 5. It wasn't blown, but the fuse was loose. So, I put a metal shim in the two holes, and everything is working now. I ended up hooking the white rheostat wire to the ICC switched 12v. That way the dash lights come on as soon as I turn the key. They only thing that's unfortunate is that the two backdoor speakers don't seem to be working. I'll have to mess with it tomorrow.

 

If it ain't one thing, it's another. I got the cd player installed and everything is working now. However, for some reason my left parking light won't turn off whenever the car is running, and the light switch is in off. When I turn the light switch to the middle position, both lights come on, and when I turn it to high, the normal lights come on. I'm just a bit stumped about why this is happening? Could it be related to the black rheostat wire? I have it wired in with the ground on the cd player because I couldn't figure out which was the ground, and which was the Rheostat.

 

By the way, the light turns off when the car is off. But it's a minor annoyance.

 

rheostat as in the dashboard light dimmer? hmmm. diagram says that *IS* a ground wire, although not one I would have hooked the stereo up to.

the 'correct' stereo ground is the black wire hooked up to the factory stereo connector D pin 6, or the factory amplifier connector E pins 1 and 14. These both go over to the right "A" post area just forward/below the passenger door lower hinge, behind the plastic panel, there's a ground strip labeled 31/10 on the wiring diagrams. This is just below the ECU, and should take standard 1/4" spade lug connectors. your aftermarket stereo should have a GOOD ground to keep distortion out, you want to use a relatively heavy gauge wire for this.

I am not quite sure how tapping into the rheostat ground wire would have effected your parking lights, unless you knocked the headlight switch connections loose while wiring it.

 

Yeah, the dash light dimmer. I hooked up the white wire to the ICC power (so the dash lights turn on when the key is on), and then wired the black one in with the radio ground (since they were both close, and figured it would be a bad idea to have something ungrounded in the dash light circuit).

I should also mention, that the left parking light burnt out yesterday, and I just replaced both bulbs. I cleaned the corrosion off of both with some deoxit. I'll check the switch, because I did take it out to examine it. Maybe something got knocked loose?

 

ICC power ?

ah, that white wire is also connected to fuse 21, which is connected to the light relay, and yes, likely might backfeed things if you hooked power up that way.

 

Do you know where the white wire should go? If it's not hooked up, then the dash lights don't get power. If I hook it up with the yellow/white striped wires, then the lights don't turn off. So, I'm at a loss.

 

you're talking to the white wire at the rheostat? or something else? I dunno *what* this yellow-white wire is, was that at the headlight switch?

The white wire is supposed to go to the rheostat. you took the rheostat out of the circuit ? I'm a little confused here.

 

I mean the white wire behind the CD player. There were also two yellow/white wires (which are the headlight wires), but for some reason they're behind the cd player as well. I kept those two connected because when they are apart, the headlights don't work. If the white wire isn't connected, then the dash lights don't work. So I wired it in with the switched 12v wire, so that the dash lights up when the ignition key is turned on.

On your wiring diagram, I'm a bit confused by what you mean by the "pins" do you mean from a plug adapter? Mine didn't have that (except into the amplifier). So, that might be why I'm confused. Or does that mean from the fuse terminal?

 

connector "D" in my diagrams is the plug that went into the factory stereo and "E" is the connector to the factory amplifier. I got adapters that these connectors plug into so I didn't have to chop any wires.

but yeah the yellow-white wires probably do need to be connected together. it goes from the headlight switch to the radio connector to the coil of the headlight relay, so no connection == no headlights or dash lights. I left that white (and blue) wire from the rheostat open, and my stuff works fine.

 

I disconnected the white wire today. Now, when I turn the switch for the parking lights, only the right parking light comes on. I have the cluster out again because I'm doing some more work on it, and waiting to install some new light bulbs, so I'm not sure if the cluster lights would come on either. Very weird. I don't have the blue wire connected to anything.

I also noticed that the rear right parking light/turn signal light is out now.

 

wait first you say only the right parking light works, then you say the right tail parking and turn is out? I'm confused.

check the voltages at the various light sockets.

its possible when you cross connected stuff, something fried. hard to guess what.

the various dashboard lights that are under rheostat control are connected between the white and blue wires (ie, there's a blue and white wire to each dash light)

 

Yeah, the front right parking light is working. The rear right parking light is out. Now that I disconnected the white wire from the CD player, the front left parking light wont turn on (whereas before it stayed on when the wire was connected).

So, what do you do with the blue and white wires that are behind the cd player? Just leave them unhooked?

 

yeah, tape them off so they don't short against anything, as those are ni parallel with all the dimmable dashboard lights.