I saw another post about the wiring for a 940 but I am having trouble putting a new radio in mine. I can't seem to determine the right battery connection to keep the settings. Which wire is the persistent battery wire?

Since all of my speakers are about shot, how do you remove the 6X9's in the back deck? I see 2 screws holding them in and a clip but I don't have enough room to lift them out. Does the back deck have to come out too?

The front door speakers look like they riveted in, if I drill those out how hard is it to put in aftermarket speakers in there?

 

can't help you with the 940 sedan rears (I have wagons), but the door speakers, yeah, drill out the rivets. these adapters make it REALLY easy to install generic 5.25" rounds in the doors, PVC Speaker Adapters - CNC Machined - In Stock or Custom Made

I had to enlarge the hole in the metal part of the rear doors that the speaker magnets fit into to fit my choice of 5.25" coaxials, and this was after removing a rubber trim bumper from the speaker magnets. I used a dremel tool with a round grinding stone to expand the hole. make sure you mount the aftermarket speakers with the terminals at 12 o'clock, as they'll probably interfere at any other position.

I was able to mount JL Audio C2-600 component woofers in my front doors by trimming the flange slightly.



I didn't use the above adapter kit, but it probably would have made it easier. I ended up replacing the self tapping screws that came with teh speakers with stainless 8-32 3/4" machine screws and nylock nuts and washers. I drilled the door panels at the right places to mount the speakers. the tweeters for these speakers are mounted in place of the factory dash speakers (which I gutted by removing the cone and magnet, then silicone glued the tweeters to the plastic basket under the original grill, so they look dead stock)

 

I put two 6.5" speakers in the front doors for now. They were rather easy to do. I will probably re-bury the cables when I have more time but they are out of the way for now. It sounds good. I put in a bluetooth capable receiver and now I can talk hands free in the car and stream music and podcasts through the system!

The only issue I have left is determining the battery wire for the yellow lead on the stereo. Now it loses my presets every time I power off the car. Anyone know what wire is the right one for this? I really wish car manufacturers would go to a standard wiring color like stereo makers have.

 

any solid red wire should be unswitched battery power. on my 92 740 t-wagon, there's a black rectangular block floating around the left of the steering column with a whole pile of red wires, these are always-on unfused power (warning, arcs-n-sparkens hide here!)

there *IS* an always on wire in the OEM stereo connector, but I'm not near my wiring diagram now ... I'll look when I get a chance.

 

Thanks Pierce. If you find a wiring diagram please let me know. I saw links to several online but most of them were no longer available. I would like to know that I have my other wiring right too. It is working but I think it is not all using the correct wires.

 

ok, on the 'green book' wiring diagram for a 1992 740/940, its green-red at the radio(stereo) connector "D" pin 9, this comes from fuse 5.

 

I will check that. Thanks again!

Now my head lights and tail lights have stopped working. Parking lights all work but when I switch to headlights the dash lights and the head lights/tail lights don't work. I checked all of the fuses in the car and they look good. If I pull back to hit the high beams they will come on but they don't work without holding it. So close to getting this thing working!

 

if turning something on causes other stuff to go out, you've likely got a bad ground, or a short somewhere. look for the ground point under the dash, it has a pile of brown wires to it. make sure your headlight relay is well seated, too, thats behind the fuses behind the ashtray... on a 740/940, its probably relay K, the 2nd from the left on the row closest to the fuses.

 

Is is it possible that the relay is bad? My shift lock isn't working either.

 

hmmm. loooking at the wiring diagram for a 1992 740/940 (your 94 is very likely identical here), power for this goes from the main "+" terminal thats under the left side dashboard (this is a black plastic rectangle with a bunch of red wires going into it, thats unswitched and unfused raw battery power), through fuse 4, green-yellow wire to connector "D" (6 pin connector near the steering column under dash), green-yellow to the brake pedal light switch to yellow-brown to the shift lock relay which is also tucked under the dash and not in the main relay panel, then brown back through connector "D", and white to the brake lock solenoid (under the shifter), black to ground at the main fuse panel.

the control signal path goes from the ignition key switch blue-yellow through fuse 9, blue-green to connector "D" to brown-white to the relay coil, pink back through connector "D", pink to the start position of the ignition switch and also to the 'start inhibit switch' (this is 'on' if the transmission is in park or neutral) and to the starter motor. sounds funky, but net effect is, shift interlock is disengaged when your foot is on the brake and its in park or neutral but the key is not in 'start'.


p.s. headlight relay is nowhere NEAR this circult.

p.p.s. when stuff that was working stops working after you did something else, ALWAYS LOOK IN THE LAST PLACE YOU WERE WORKING