1978 280z No Power to the Starter

[rossiz]

Hey all,

Been lurking for a few months, slowly restoring my new-to-me 78 z and loving it, BUT...

I've hit a wall with an electrical problem concerning the starting system. Some background:

I replaced the fusible links with maxi-fuse blocks, located in the cabin by the fuse board on the passenger side

Moved the relays from the engine bay to inside the cabin, back of firewall under the heater fan

Re-made the primary wire loom from the battery to the new maxi-fuse blocks and new 8GA leads to the starter

New battery, plenty of juice, lights work fine

The car started fine, ran great for several weeks, drove it to work and came out at the end of the day, turned the key and and NO response from the starter. No clicking, solenoid silent. Lots of relays clicking around in the passenger area under the dash, but no love. The accessory functions light up, seat belt buzzer sings, etc. just no starter.

Looking at the FSM I identified the "Ignition Relay" and thought this might be the issue - cannot find a replacement part anywhere on this earth.

Took apart the unit and while I don't really understand how its supposed to work, both relay solenoids activate and deactivate when I turn the key switch to "ON" and "Start". Further reading/searches seem to indicate this relay actually doesn't even fire the starter solenoid at all...

If I arc a screwdriver across the big terminals on the starter solenoid, the starter motor spins up. If I arc from the positive terminal on the starter solenoid to the B/Y small gauge wire (spade connector) on the starter solenoid, I hear a big 'click' and the starter motor spins, but the gear doesn't engage to crank the motor.

All my fuses look fine (newly replaced when I bought the car) and I'm totally flummoxed at this point... Could it be the ignition switch itself? Where should I start looking?

Thanks in advance, any help would be greatly appreciated

[Zed Head]

Connect a jumper wire to the small connector on the solenoid (the one that can be pulled off by hand, yellow wire) and hold it to the battery positive post. That should actuate the solenoid, causing its plunger to move, which should then actuate the motor relay and drive the starter gear in to the flywheel. It's what the ignition switch does. It sounds like what you're jumping at the solenoids is just bypassing the solenoid's internal relay. Jumping the solenoid directly from the battery will tell you if the starter is good or bad, then you can focus forward or backward from there.

[rossiz]

Thanks Zed - will try asap.

[rossiz]

okay, my bad on the starter solenoid - when i put it back together the first time i didn't have the little actuating arm (that goes down to the starter relay) hooked properly to the plunger rod. got it right, and now when i jump from the positive contact (big red wire on the solenoid) to the small spade connector on the solenoid, the starter engages and cranks the motor. all good there.

still no love from the key switch though...

are there any typically suspect connections between the key switch and the solenoid, or is the switch the first place to look?

i have the covers off the steering column and am stumped about how to get the key switch bracket off the column - of the 4 fasteners that clamp it on, the two diagonal are philips head and the other two are some sort of round, solid head security screw. ??!? do i have to drill these out? seems iffy to me...

[siteunseen]

Those 2 "Security" screws are a PITA. I used a Dremel to cut a slit in them and then a flat screwdriver to turn them out. One good thing is they're not too tight so just a small slit will give you enough grab to turn them. Leave the phillips head screws in to keep weight off while you work them out. You might could use one of those extractor type drill bits to get them out, I don't have one but do have a Dremel. It's not too hard, just slow, and you have to be extra careful around the wiring.

[rossiz]

well... turns out it was the key switch.

lock tumblers all worn out and it wasn't letting the key turn all the way to the "Start" position. with a bit of wiggling and getting the key just the right depth into the switch i'm able to get it to work.

now, is there a relatively simple way to replace the lock cylinder to fix this?

[Mark Maras]

Take it to your local locksmith & let him take a look at it. The chances are good that he can repair it. Should you decide to replace it, you'll need to take it to him anyway to have it re-keyed. Virtually the same process as repairing the old one.

Mark in Portland

[Zed Head]

You could also put a little extra twist in the flat rod that connects the cylinder to the electrical portion. Two pairs of pliers will do it. I had the same problem.

[rossiz]

Well, I managed to get the security screws out and took the lock cylinder apart. Yanked out all the lock tumblers except the one at the top that rides on the key shoulder and activates the black plastic eccentric ring/switch. At least this way you need a key and can't just start it with a coin... It works fine now, even though it's pretty loose - reminds me of all the old classic cars I've owned which had worn out ignition switches and you could take out the key while it was running. The important thing is that I now have some confidence that I'll actually be able to start it in the morning!

Thanks to all for your help/advice. The sun peeked out for about 4 hrs. this afternoon and I managed to get the z washed and ripped around town for a while - exactly what I got this car for

[no.never]

nicely done sir.

mine has the same stupid problem, but it's intermittent. i started checking it last weekend and it was driving me mad. a dead battery doesn't help either. such a newb.

it sucks when you get back from your lunch break late because the car wouldn't randomly start yet five minutes ago it started like a dream.

[no.never]

i got a chance to check my 78 2+2. i think the harness at the back of the switch was slightly loose so that could've been my problem. starts right on the money now.

reminds me of all the old classic cars I've owned which had worn out ignition switches and you could take out the key while it was running.

ha, i forgot that mine also does this, so i'm most likely going to have to replace/fix the switch anyway at some point. i saw those screws, how did you end up dealing with these punks?

i'm guessing:

I used a Dremel to cut a slit in them and then a flat screwdriver to turn them out.

which is what i'm going to try.