Jeff Berk

CO.. I had to go back to the car and check but yes, with the G&L jumpered, the fan does obey the speed control and I get the 4 speeds and off. I do hear the relay click when the ignition is turned on with the relay connected. With the relay disconnected again, I'm seeing 12V on the non-diagonal L wire. Interesting that I'm seeing 0.1V with the ignition off. The relay appears to be grounded to its shell; however, there is a fourth wire on its connector (seen in the photo as a head-on view) that has no matching wire on the mating harness connector. This could be a ground that Nissan chose not to implement. The fan relay is just to the right of the "Ground" tagged wire. The ground wire was added because I was worried that there were too many ground wires from different components connected to a single grounding wire in the harness and was a potential cause of some wire melting events I experienced. To the right and up a bit are two screws that mount the power relay to the relay panel. That is how the relay shell is grounded. As you can see, I went a little crazy with the label maker. JB

Well... when I jumper the L & G wires the fan runs at full speed even with the ignition off. Questions: 1) I'm assuming that means I have a bad relay. 2) Can I rejuvenate a relay by opening it up and cleaning the contacts? 3) Can I use a modern relay or do I need to hunt down another used one and keep my fingers crossed?

Thanks CO, that's a start. Diagram BE-53 shows fuse 5 counting down on the left side powers the blower. I'll clean it up as well as the fuse-box clips. I'll also try what you suggested for the relay. I had replaced it with a used relay because the original one had a fried wire. Thank you for the help on this. I'd like to get this working so I can drive this car into late fall.

I've been at this for some time so I need some idea what to try next. Background: This is a '74 260z that formerly had an A/C. The original controls are still there but the vacuum tubes are disconnected. The fan was not working. 1) I removed the fan and when I applied power to the blower motor connector, it ran at full speed. 2) I checked the blower control switch using a continuity meter and each position seems to work. 3) The power relay puts out 12 volt with the ignition in the on-position. 4) I verified the proper electrical connections using the color codes on the attached figure and there are a lot of them. 5) I traced (using a continuity tester) the Green wire from the power relay to the heater connector where it became a white wire to the blower motor connector. The voltage at the white wire on the blower motor connector ranged from 12 volts (fan of) to less than 1 volt at the 4 setting. I'm a little confused as to how this is supposed to work and why the fan should be off (which it is) at 12 volts when if I remove the fan and apply 12 volts directly to the blower motor connector the fan runs. Can anyone tell me what to try or test next? Thanks for your time... Jeff

I ended up purchasing a 1/2 in MIP x 3/8 in FIP brass pip reducer bushing. It seems to be the right threading but I did get a little bit of leakage. I tightened them down some more and we'll see if it holds. Thanks for the work.

The one you have sounds like the one I have right now. I purchased this one: https://www.summitracing.com/parts/sum-890115 They also sold me a radiator hose adapter to install along with it but I don't want to go that route if there is a way of connecting the thermal sensor directly, especially at $50. https://www.summitracing.com/parts/atm-2283 The plug on the thermostat housing looks more accessible so I'll unscrew it and take it to a hardware store and maybe I'll bet lucky.

On making the old system work again, the old system looks kind of beat up (missing control knob, no enclosure box) and has some odd wiring (one wire going to the coil). I can try and open it up and look for a relay to replace, but I'm not sure if that's the issue. Summit Racing had a screw-in sensor that looks like the one 7tooZ posted but it has a 3/8-inch pipe thread. What type of threading is used on a Z? I noticed that 7toZ has a bushing on it. Is that a NPT to some type of metric bushing? If so, where do you find such an animal?

I am going to be at Summit racing tonight to pick up another item. I will talk to their technicians there to see what they suggest. Thanks… Jeff

I am trying to figure out the best way of controlling the electric radiator fans in my 260 Z. The previous owner installed dual electric fans operated by a thermostat with a temperature probe in the upper radiator hose connection to the radiator. The temperature switch no longer turns off the fan so that even when the car is cold the fan is running and I need to pull the fuse. Would it be best just to replace this with an identical unit or should I install a temperature sensor in place of the threaded plug of the thermostat housing? If so, does anyone have an idea what the threading is on this plowed? Thanks for reading this… Jeff

I purchased this harness thinking my old harness was bad. I was wrong so I'm keeping my old and selling this one. I've cleaned all the contacts and re wrapped it with cloth tape. I added an extra ground wire because I've had problems in the past with the original ground configuration. One connector housing is slightly damaged but still works fine. Most of the terminals have been labeled. This is reportedly off of a '74 with a manual transmission. I tested it out in my car and it seems to work fine. I'm asking $95 including shipping from Cleveland, Ohio. You can take $8 off for local pickup.

I spoke with someone who came up with the same answer, a 10 amp breaker. I'd like to replace the missing contact to split up the power between fuses Nos. 3 & 4. Does anyone have a spare clip they are willing to part with? I guess another option would be to install an in-line fuse to replace the missing fuse location.

Missing a connector in the fuse box. Vehicle 1974 260z 2-seater The attached photograph shows the backs of my fuse box on the right and one I purchased on the left. The fuses are numbered top to bottom 1-7 on the right and 8-14 on the left of each box when viewed from the rear. The outer contact on my fuse No. 4 is missing. Someone spliced a purple box marked 12V10A 410 (upper right side of photo) branching off of the Green/White wire from fuse No. 3. A blue wire then extends from the purple box. I’m assuming the blue wire used to go to No. 4 based on the wiring of the box I recently purchased. All would be fine except fuse No. 3 keeps blowing. I’d like to reinstall the missing AGW fuse clip and run the blue wire back to its own fuse. At last, the question: Where can I purchase a replacement AGW fuse clip? A side question: What is this purple box and why was it installed?

If you still need some answers to your questions... There are two screws holding the tach in that are accessible from under the dash and under the top overhang of the tachometer hood. Once these are out, I think you just reach back and push the tack forward and pull it out from the front. You might need to remove the steering wheel to get it out. If you have a dash cap installed, it will likely need to be removed. Your can then attach lead wires to it. One to the + side and one to the - side of the battery, then one more to the - side of the coil after first passing through a 50 kohm resistor. That will at least tell you if the tach is at fault or if it's a problem with a loose wire or bad resistor. Let me know if you need a resistor. I have extra after setting up some test leads for this very issue. Jeff

I think someone rearranged the wiring on that 260z. The fusible links should of been on the firewall. That white plastic thing and the "emergency" switch should of been where the fusible link holder is now.

Fantastic resource! Thank you! I'm assuming because the N3600 says MANUAL and the N3601 doesn't specify, the latter is for an Automatic. I might try the N3601 in my manual Z since they seem similar. I'll just check for any changes in the plugs or wiring colors as I hook it up. Any idea what the ER stands for? Jeff BTW, I just had my Z out last week for my first ever SCCA autocross. I was just about the slowest person out there but had a lot of fun. Luckily with my gauges not working (except the spedo) due to electrical problems, my tach didn't work. That way I didn't have to worry about redlining it.

I have a 260z with some electrical issues. I was going to try and replace the wiring harness and purchased one off e-bay. The under dash harness on my car has a label with the part number 24013 N3600 but the one I purchased has a part number 24013 N3601. They both seem to be the same so I don't understand the number difference. Is there a list somewhere with the part numbers used on the 260z? Jeff

JSM... Thanks for the info. I have no idea where the velocity stacks originated from. I had to wrap the ends of them with self-vulcanizing electrical tape to build up their diameters so that I could install an air cleaner. The Air cleaner/filters were just inexpensive universal units I purchased from Autozone. I know it was jerry-rigged but less so than that of the PO.

Hi all, I have a '74 260z with a 280 engine/5-sp manual that I purchased a few months ago. In the early 80's, a triple carb system was installed in it. Then around 2010, it was changed back to a dual SU carb system. I was trying to adjust the carburetors and could not locate the fast idle screw. After some digging on the internet, I think it's missing (see second picture), maybe during the switch back to dual carbs and the addition of the nifty bolt as a vacuum plug. Is this something I can easily fabricate out of a triangle of thick sheet metal with three holes, a screw for adjusting and maybe a spring around the screw? If not, anyone can suggest a source for this missing part? Also while I'm at it... The first picture is of the bottom of one of the carbs. Is the knurled nut just below the carb the air/fuel ratio adjuster? Thanks! Jeff