anthony_c

"...wire the car to use the ignition to power the relay coil and get a 78 oil pressure sender. Swap in a typical automotive relay..." Any solution that bypasses the original relays. They have become a perpetual nuisance. @SteveJ do you have a preferred place to connect the relay coil w/o cutting existing wiring?

i like it, my only concern is that is a one-off product. what happens when it fails and replacements are nla.

the 260 has (or at least mine does) two factory fuel pump relays. one triggered by the alternator, the other by the interlock relay. and if i could i would yank the whole mess and switch to a mechanical fuel pump.

it's been several months since i looked at the wiring diagram, but before your completely bypass the interlock watch out for the fuel pump relays. one of them is triggered by the interlock system.

yes i do. for the sake of not having to exercise that knowledge at the roadside i would still like to install a new relay and find a different power source for the coil side.

"The first place to check the voltage on the yellow wire is at the voltage regulator." - I'm measuring 7.5v on the yellow wire at the alternator and at the relay. Enough for the original relay but not the new mini-cube. and now it magically works again. ughh. would rather it stayed broken long enough to identify the fault.

"need a relay with a pull-in lower than 8 Volts" @Captain ObviousI dare you to try that line at your local parts counter ?

@SteveJThanks for the clarification. I have been referring to the diagrams but didn't realize FPR2 was NC and served as a kill switch when the starter was activated. For the record I couldn't understand why they were pulling coil power from a circuit that was only active when the starter was engaged, but now it does make more sense. As to why I'm working on this, the P.O. must have run into a problem at some point and hastily re-wired the relays in a rather non-conventional manner, pulling coil power for FPR1 from the fuse panel and bypassing FPR2 entirely. I was trying to normalize what he had done and make the arrangement closer to stock but suspect I have encountered the same issue he did. I'm not getting enough voltage from the alternator to consistently trigger the relay. Sometimes it works, sometimes not. I took the alternator to a local remanufacturer and they could not identity the problem, so I purchased a reman alternator from ROck Auto. Same issue. I'm not getting enough voltage to trigger FPR1. Hoping for an easy fix I picked up a new generic 4-pin relay from Napa but that was no help either. At this point I probably need to start working my through the harness to find where the voltage drop is occuring. My suspicion is the patch panel under the dash on the passenger side. Those mini-bullet connectors seem to be the cause of many of my problems.

260 actually has two fuel pump relays, one controlled by the interlock relay, the other by alternator, both by way of a yellow wire. neither is putting out enough voltage to reliably trigger it's respective relay. for the moment i'm just using one of the relays and inserting jumpers as needed to get power to the fuel pump. and yes, everyone is helping! thank you.

my initial guess was that the original relay had failed so i picked up a generic mini-cube type relay at napa. after some additional testing i found the voltage on yellow is hovering around 2v. if i crank the starter it rises to a max of 8v. probably not the relay.

reference "interlock relay" and work backwards from there

Most of Bosch's relays show a pull-in voltage of less than or equal to 8v but they don't explicitly indicate a minimum. Did they mean >= 8v, or is the stated drop out of 5v also the minimum pull-in.

does anyone know offhand how many volts it takes to trigger one of the bosch style mini-relays?

As SteveJ mentioned earlier, in order to run LED's on a US spec 74 260z I would need to re-wire the dimmer switch to switch on hot instead of ground. I'm not prepared to go that far so will probably just drop in a relay and be done with it. Depending on amp load I may upgrade to halogens, but tbd.

AK260, In the states we look for the "D.OT. Approved" label. Lots of options on amazon, none with a brand name that i recognize.

Yes, I first encountered the directional issue with led's when I installed a dome lamp. Had to scratch my head for few moments. Reading the packaging proved even more helpful. I spent some amount of my life going through the wiring diagrams before I fully understood the 'what' and 'how' of their 1 positive/2 grounds wiring of the headlamps. Yes it works, but the "why did they do it that way?" still eludes me. The only reason I can think of is that it splits the load across two fuses without adding an extra set of contacts in the dimmer switch. Oh well.

I'm sort of in the place. The headlight relay kit isn't available for the 260, so I'm thinking LED's are good interim fix until builld my own (working on specs for that now). And I agree, 3000 is a more comfortable color. I use 2700 in my home. Is that an LED bulb in a generic H4 housing, or something similar to the eagle lights that w3wilkes is using?

Looks like a decent price, but with a 6K color temp i hope we don't cross paths with those things on.

@SteveJ , which of the LED headlamps did you finally settle on? Thanks, Anthony

fair warning: i can be long-winded, you may regret that offer. its a 260 with a 7/74 build date and problem is intermittent. either the starter responds immediately, or it doesn't respond at all. not so much as a peep from the solenoid. meter confirms no current being delivered to the yellow wire on the solenoid when i turn the ignition to 'S'. to-date: replaced starter. works better than the old one, but didnt fix the intermittent issue replaced the battery, not really related to the problem, but needed anyway following SteveJ's advice i put in a jumper at the emergency switch. i was convinced that was going to fix the problem but it didn't. (back to the wiring diagrams looking for problems upstream) i've had problems with other connectors being flakey, and this isn't the first time i've dealt with that panel under the dash. a few years ago i spent a few months with a meter tracking down an unrelated problem. the meter picked up a fair amount of resistance there and elswhere so i went around the car with an emory cloth and vinegar, cleaning contact points. picked up a volt or better in the process. after the previously mentioned mechanic clipped the w/r wire and bypassed the panel the starter responded immediately. it was a noticeable improvement, but the intermittent problem returned again. i didn't like his solution, but it did give me some confirmation of where or what the problem is. on a whim i reached over and pushed c1-c5 in just make sure they were snug, hit the ign switch and all was good. whether its oxidized or loose contacts, my suspicion is these connections have reached end-of-life. if i can't reasonably get the plastic connector out of the panel then i'll drop back and try one of the pin extractors.

a few things: ive got a bad connection somewhere in that panel which is preventing the car from starting 50% of the time. some of the lock/release tabs have broken off, so the connectors dont always stay seated. would like to completely bypass interlock system and possibly lay new copper from ign switch to solenoid. i've studied the wiring diagrams and it looks pretty straighforward, just need to verify the wiring actually matches the diagram. a local mechanic clipped one of the w/r wires, bypassed the panel, and did a butt splice to get the car to start. it worked for the moment, but it wasn't the only problem and the solution is less than elegant. he received a stern scowel. with regards to mechanics and body the car is in fantastic shape, but need to do something about the electrical gremlins. at this moment still studying, but one option is to re-terminate with generic after-market connectors and be done with those problems once and for all.

@Captain Obvious, you left out a few "PITA's". I have a spare harness that i was able to experiment with, and if it is that difficult on my living room floor i will assume it is damn near impossible upside down and backwards in the pasenger foot well. Not prepared to start destroying perfectly good parts so i'm going to ponder my navel a bit longer and hope a solution presents itself..

?tried some tappet gauges but couldn't past the tabs. will try soapy water next.

found something similar on amazon. https://www.amazon.com/Kalolary-Terminal-Electrical-Connector-Extractor/dp/B07BBM1MK4/ref=pd_lpo_vtph_107_bs_lp_tr_t_1?_encoding=UTF8&psc=1&refRID=WWWGQV7EQQP7MB89ZPKA i've not used one of these before. is there a group favorite? the connectors appear to be held in place by 4 small tabs on the backside of the panel. i could probably pry them out, but this would likely be damage to the connector or panel.

if my experience is any indication, that dash would have split if you had parked it on a shady mountainside in west virgnia on a cool spring day. these plastics are becoming my nemesis.