Ignition not cranking the engine (only click is heard at starter)

[Captain Obvious]

11 hours ago, Zed Head said:

Might be that there's a seat belt switch that actuates the Inhibitor Switch which then actuates the Starter Relay allowing the starter to function.

Yeah, I think it's a naming problem. I've looked the diagrams over and even though they call that thing a seat belt relay, I cannot find any connection between the seat belts and that relay. The switch in the seat belt buckle only actuates the buzzer. There is no interaction with the starter at all.

And the inhibitor switch is on the transmission. It is closed only when the transmission is in PARK (and probably NEUTRAL). In other words, if the transmission is in reverse or a drive gear, the starter will not crank. You have to have the trans in "P" to start the car.

 

[Captain Obvious]

10 hours ago, Zed Head said:

Something that the electrical guys might be able to explain - does this diagram not show power from a fusible link passing through two normally closed relays to a realu coil then to ground?  Can't be right, right?

Confusing diagram. I think they are trying to show "this is how it looks while in use". I think you are correct in that the nomenclature for normally open and normally closed is wrong in that diagram.

[Zed Head]

EuroDat added a dotted green line from the inhibitor switch to the seat belt switch.  Maybe he had the same thoughts.  Maybe the dotted line means maybe.  It's not shown in the FSM original.

He also changed the closed relay to open.  Normally closed seems to make more sense since it would complete the buzzer circuit unitl you opened it by fastening the seat belt.  Maybe.  Oh well, just another puzzle that Nissan left us.

[Captain Obvious]

The diagram (created by @wal280z , not Eurodat) says the dashed line is for Canada. And there's still no link between the seat belts and the starting of the car. They just changed how the belts and warning light and buzzer get connected.

[Captain Obvious]

So Zedhead posted a good pic of the starter relay earlier... it's up in the engine compartment in front of the battery.

If you disconnect the starter relay and short the two black/yellow contacts together (on the car side of the harness), it will take both the starter relay and the transmission inhibitor switch completely out of the starting circuit. In other words... With the two B/Y wires shorted together, when you turn the key to START, the starter should spin even with the transmission in drive.

If it still fails to crank even with that jumper in place, then it's something other than the starter relay or the transmission interlock.

 

Edited February 6 by Captain Obvious

[MH77280Z]

Update:

Cleaned all 4 grounds (engine, intake, firewall and AFM) - same result - only click at passenger relay no power to starter

Cleaned all 4 contacts under the car at the inhibitor switch - same result - only click at passenger relay no power to starter

Took off starter relay and shorted two BY connectors - same result - only click at passenger relay no power to starter

What next? is this click at the passenger relay panel coming from ignition relay?

 

 

 

8 hours ago, Captain Obvious said:

So Zedhead posted a good pic of the starter relay earlier... it's up in the engine compartment in front of the battery.

If you disconnect the starter relay and short the two black/yellow contacts together (on the car side of the harness), it will take both the starter relay and the transmission inhibitor switch completely out of the starting circuit. In other words... With the two B/Y wires shorted together, when you turn the key to START, the starter should spin even with the transmission in drive.

If it still fails to crank even with that jumper in place, then it's something other than the starter relay or the transmission interlock.

 

 

[Yarb]

So you are talking about the relay box on the fender well inside the engine bay correct?

[Zed Head]

The built in tool and parts shelf.

[MH77280Z]

Yes the relay was on the right side of it. This one…

I had a spare one tried this too.

[MH77280Z]

Can it be ignition relay?

On 2/4/2025 at 7:50 PM, Zed Head said:

I don't know why Nissan calls that relay a Seat Belt relay.  Hard to tell by the wiring diagrams.  Looks like the seat belt buzzer has its own circuit.

They show the "driver's belt switch" here but not in the starting diagrams above.  Confusing.

 

[Yarb]

The relay at least on my 78 is inside the black box

[Zed Head]

It could be.  That picture I posted in #17 is the one that came from my car.  It was bypassed with a wire.  Not sure what else did not work before I replaced it.  

It's not too hard to get to.  Unplug it, remove the screws, and pull it out.  If you're good with a meter you could do some testing.  Post #19.  Easy to open also, just bend the tabs back.