C/S Repaired, Parking Lights work, don't when Headlights On!

[moritz55]

I recently bought a 1973 - 240z. I just disassembled & cleaned the Wiper Switch, Turn Signal Switch and the Combination Switch. As a result, hazards flash brighter, wipers are faster, the dash lights now work(did not before) and the parking lights & headlights are all brighter. This is the good news.

The bad news is that when I turn the combination switch from Parking Lights --> Headlights, the dash lights/parking lights go out! For some reason they don't stay lit. I pulled out the C/S and validated the switch appears to work properly. I confirmed continuity across the parking light (green wires) in both parking light and headlight positions, while the headlight continuity is only measured when in the headlight position.

I'm a bit baffled, and have cleaned the grounding connections, validated the fuses work and haven't been able to find a fusible link to see if this is a problem? I don't think this car has a fusible link?

Can anyone give me some debug tips? I'm at a loss right now - many thanks.

[Zs-ondabrain]

Defenetly start with the grounds. Sometimes the headlights can draw too much ground from the parking lights. I know that sounds totally wrong and weird but hear me out.

The front parking lights are grounded thru a single wire that connects to the larger gauge wire that bolts to the alternator and then to the body, on the frame below the battery. (across from the starter) The front side markers, parking lights and front turn signals as well as the Voltage regulator and underhood inspection light ALL use the same Small gauge ground wire.

Every ground in the dash area uses the SAME 10 gauge wire (noted above as bolting to the body, just above the frame rail, near the starter) START HERE!!!

Also look on the upper right side passenger kick panel for that same ground wire and check the connection there as well. The headlights use that ground wire to control the HI and LO beam. If the headlights draw too much from that ground wire because of a bad connection, the parking lights may suffer because of it.

Check yer grounds and go from there. Also check the combo switch and the connector plug for proper connection.

Good luck,

Dave.

[moritz55]

Thanks Zs-ondabrain, you've given me enough to focus on. Is there somewhere I can find exactly how many Ground Points/Conections to the body exist on the 1973 240z? You've given me 2 Ground points to work on.

1) On the frame below the battery. (across from the starter).

2) Upper right side passenger kick panel for that same ground wire and check the connection there as well. The

[Zs-ondabrain]

Double check the switch with an ohms meter. test the solder joints on top of the combo switch (green/white green/blue) there should be 0 ohm between them with the parking lights on and 0 ohms with the headlights on also.

There are only 2 explanations for the parking lights dropping out when you turn on the headlights. 1) the switch is not making contact on the inside when the headlights are turned on. 2) the headlights are somehow drawing all the ground from the parking lights.

Loosen and remove the ground wire screw/bolt near the frame, find a wire wheel dremmel bit or stiff wire brush, brush the hell out of the contact (ring terminal with 2) 10 gauge wires on it) and clean the area aound the screw/bolt hole. then rescrew/bolt it down, nice and tight.

The headlight circuit is completely separte from any other circuit in the car. Therefore, it has to be a ground problem. I've checked 3 other diagrams and found NO particular ground points other than those I already pointed out earlier.

The only other possible ground points would be where the dash is bolted to the inside of the car. Behind the radio is a "U" shaped bracket (bolted to the trans hump, that has 2 side brackets that attach to the dash. Check the bolts there and make sure they are tight, with a socket or wrench (10 MM).

Hope this helps a little more,

Dave.

[moritz55]

Sorry, I sent the reply to quick.

I did clean the grounds on the regulator/capacitor and alternator, also the one under the dash center console (near the fuse box). Once I complete the 2 you mentioned, I'll let you know how I make out.

I'm traveling this week and will get to it 8/6 .

Many thanks !

[moritz55]

I completely cleaning the grounds, both the one below the battery near starter, and the other one above the passenger kick plate. They were very very corroded. I also found a secondary ground wire (10 gauge I think??) at the battery terminal end that went to the frame. It was not tightly connected to the terminal clamp so I tightened this up and also cleaned it good.

I turned on the parking lights and they work along with the dash lights same as before. Then I turned on the headlights and they worked fine but the parking lights went off again similar to before.

My next task will be to check the C/S switch as recommended to see it I read 0 ohms between green/white green/blue wires when switched on.

Stay tuned and many thanks, Mark.

[graham53]

I had a similar problem. I had changed the bulbs and thought i had used 1157 but it was 1156? did you change the bulbs?

[moritz55]

I completed the debug effort with the help of Zs-Ondabrain guidance and have confirmed I have a bad C/S switch in the Parking Position Only. The actually I can see that the spring/button retention socket ion the Parking Switch side is missing (has broken off) a small tab that keep the spring/button retained when I switch to Headlights On. Actually when I reassembled the switch and confirmed 0 Ohms across both Parking & Headlight positions - I was optimistic it would work. However after cycling the switch several times, the Parking spring/button kept falling out of it's socket, that's when I noticed it was missing a small upright tab that retains it when you turn Headlights & Parking Lights toward the OFF position.

Anyway - on to finding a replacement C/S Switch for my 1973 - 240z .

Does anyone know where I could get a refurbished or replaceemnt C/S switch?

ps.... DAGZEE , I did change all the buldbs and clean the contacts, that's how I got them to work originally after I cleaned the combination/switch .

Many thanks.

[MikeW]

Does anyone know where I could get a refurbished or replaceemnt C/S switch?

There's one on EBay right now:

http://cgi.ebay.com/ebaymotors/datsun-240Z-light-wiper-switch-clean_W0QQcmdZViewItemQQcategoryZ50459QQihZ020QQitemZ300136899706QQrdZ1QQsspagenameZWDVW

I have one that appears to be almost new. I bought it to replace mine without realizing that intermittent wipers were added for 1973 and the connector is not the same.

[moritz55]

MikeW, thanks on the eBay auction, I missed it by the time I read this.

Does your extra C/S switch come WITH intermitent wipers or WITHOUT. Looks like mine is a slightly older 1973 version WITHOUT intermitent wipers, just speed positions (Slow --> Fast). The one I have has the square 6 pin white plastic connector (not a rectangular white one).

I'd be interested in buying it. How much would you sell it for and include the shipping costs to Rochester, MN 55902 ?

Many thanks ,

[MikeW]

I'll have to look at it when I get home but as I recall the switch in my '72 has a 4x2=8 wire rectangular connector and the replacement I bought is 3x3=9 wire square connector. That makes sense given the need for the extra intermittent wire. It sounds like your car is a very early '73.

[Zs-ondabrain]

I figured it was the switch but it never hurts to refresh your grounds. Don't forget that I still do the C/S T/S service for $40.

I rebuild what ya send me. $40 for each set (1-T/S switch and 1-combo switch) I promise to make them as new as possible. them send them back. It's what I do.

Dave.