1973 240z Blower Motor

[JW240]

Morning all, I was wondering if someone could help, i have looked online but found nothing.

When reinstalling my wiring loom I have noticed there is no power from the blue wire that feeds the blower sub harness. The grounds are all ok so I used the wiring diagram and found this wire becomes a blue with red tracer stripe, followed it along and i have no 30 amp fuse, so checked the fuse in the fuse box and its good, the relay it goes too works also.
I'm not great at wiring and I'm now thoroughly frustrated by the lack of power here. It all worked before i took it out for paint, the blower itself is all fine just no power from that wire!!

 

[jonbills]

I might be wrong, but it looks to me like the blower is supplied direct from the hot (permanently live) side of the fuse box via that blue/red wire (and that wire coincidentally supplies the accessory relay and circuits) which is why it needs it's own 30A fuse.
You say you have no 30A fuse - do you mean there's no fuse or fuse holder, or just that the fuse is missing?

do you have power at the blue/red wire at the fusebox?
do you have power at the blue wire that supplies the 30A fuse holder?

 

[JW240]

I might be wrong, but it looks to me like the blower is supplied direct from the hot (permanently live) side of the fuse box via that blue/red wire (and that wire coincidentally supplies the accessory relay and circuits) which is why it needs it's own 30A fuse.
You say you have no 30A fuse - do you mean there's no fuse or fuse holder, or just that the fuse is missing?

do you have power at the blue/red wire at the fusebox?
do you have power at the blue wire that supplies the 30A fuse holder?

I don't have the fuse holder, looks like there never has been one.
The blue power wire is quiet short an immediately disappears into the loom, doesn't look like there i s space for one and the loom wrap seems original.
I haven't checked for power at the fuse box yet, need to get a mulimeter as my electrical ability is lacking.

 

[jonbills]

definitely easier with a multitester
Are you sure you've got the right wiring diagram?
where'd you get the diagram? Where's the car from?

 

[Rob Gaskin]

I don't understand that diagram. If you look at the switch it would short out the power and blow the fuse in the top position.

From memory (I'm not at home) power is switched to the motor (once the switch is rotated from the off position) and the same switch (via a different circuit within it) sends a 'ground' to the motor via the resistors which are located in the housing and cooled by the fan. The different speeds of the motor are controlled by the selection of resistors.

 

[JW240]

definitely easier with a multitester
Are you sure you've got the right wiring diagram?
where'd you get the diagram? Where's the car from?

I found the diagram here http://datsunforum.com/datsun-240z-sport-1971-fsm-supplement/
My car is a US delivered 73, so I think this is the correct diagram

 

[JW240]

I don't understand that diagram. If you look at the switch it would short out the power and blow the fuse in the top position.

From memory (I'm not at home) power is switched to the motor (once the switch is rotated from the off position) and the same switch (via a different circuit within it) sends a 'ground' to the motor via the resistors which are located in the housing and cooled by the fan. The different speeds of the motor are controlled by the selection of resistors.

Im that rubbish at wiring i didn't even notice that.
The switch for the fan speed seems ok, if I run 12v from the battery into the sub harness power wire then the blower works and the individual speeds all work, its just the lack of power here from the harness.

 

[Rob Gaskin]

Im that rubbish at wiring i didn't even notice that.
The switch for the fan speed seems ok, if I run 12v from the battery into the sub harness power wire then the blower works and the individual speeds all work, its just the lack of power here from the harness.

Your solution is what the previous owner of my 240 did. So the motor was live all the time and no fuse!

That too was a US car.

 

[JW240]

Well, it turns out the 3 pin relay in the passenger footwell is grounded via the body.
I traced the wire going back and it stays blue, totally different to what the FSM states. But just for future reference, some of the relays are grounded via the metal cases and some arent.

 

[Rob Gaskin]

Well, it turns out the 3 pin relay in the passenger footwell is grounded via the body.
I traced the wire going back and it stays blue, totally different to what the FSM states. But just for future reference, some of the relays are grounded via the metal cases and some arent.

Are you saying your blower has a relay in the circuit and that your's didn't ground so was the fault. From memory I didn't think there was a relay in that circuit. I'll check my diagrams. The passenger footwell on your car is the RHS?

 

[JW240]

Are you saying your blower has a relay in the circuit and that your's didn't ground so was the fault. From memory I didn't think there was a relay in that circuit. I'll check my diagrams. The passenger footwell on your car is the RHS?

I am indeed, it received power from this relay when ignition is on, meaning the centre panel back lights are on when the key is, no matter what the headlights are doing.
The loom was all OEM tape and was nothing like an of the wiring diagrams.
I traced the blue wire back, it stayed blue, then ran into a 3 pin relay on the RHS footwell, I think the relay is 25230 89914 (shown as wiper relay I believe) the constant 12v and switched 12v are also solid blue wires, these run back towards the fuse box where one runs through an inline fuse and the other meets up with about 4 more solid blue wires at a factory splice. No wonder I couldn't diagnose it via wiring diagrams. For reference mine is a febuary 73, factory manual, north america car.

 

[Rob Gaskin]

I think you have some fundamental problem with the circuits and yes the diagrams are notoriously inaccurate (and in some cases not electrically correct). I'm back at home now and will try to help but I gave a lot of my diagrams (home drawn) away with my car.

I relocated all my relays to the glove box (rally car) and none of the relays required to be grounded - they weren't because I attached them to an aluminium plate which wasn't grounded. The picture is just to show the 'standard' relays i.e. wipers (blurred far right of photo - not the one in the centre, that's for my Honda wiper motor) , horn, indicator and hazard units.

 

[JW240]

I think you have some fundamental problem with the circuits and yes the diagrams are notoriously inaccurate (and in some cases not electrically correct). I'm back at home now and will try to help but I gave a lot of my diagrams (home drawn) away with my car.

I relocated all my relays to the glove box (rally car) and none of the relays required to be grounded - they weren't because I attached them to an aluminium plate which wasn't grounded. The picture is just to show the 'standard' relays i.e. wipers (blurred far right of photo - not the one in the centre, that's for my Honda wiper motor) , horn, indicator and hazard units.

View attachment 47364

This is how it should have looked, the problem I'm finding is there is so much mis information out there, people mistaking modified cars for standard, multiple changes at each year and 3 main markets where the wiring varied. I even used a modern 4 pin relay to check and the ground was the issue. Not sure if mine was a friday afternoon car but the wiring is just bizarre in places.
On the note of now having no indicators im going to try and swap the hazard and indicator relay and see if the problem moves, if it does, then itsa simple fix (doubt it) i take it two pin flasher relays are generic?

 

[Rob Gaskin]

This is how it should of looked, the problem I'm finding is there is so much mis information out there, people mistaking modified cars for standard, multiple changes at each year and 3 main markets where the wiring varied. I even used a modern 4 pin relay to check and the ground was the issue. Not sure if mine was a friday afternoon car but the wiring is just bizarre in places.
On the note of now having no indicators im going to try and swap the hazard and indicator relay and see if the problem moves, if it does, then itsa simple fix (doubt it) i take it two pin flasher relays are generic?

The hazard relay carries a greater current (all bulbs not just one side) so I'm not sure how decisive that will be. There will be stamping on the case which will show the current and number of bulbs.

If your wiring looks standard then that's a great start. The slicing inside the looms is a real problem when tracing and I ended up unwrapping my looms but I was doing a major job and modifying everything.

 

[JW240]

The hazard relay carries a greater current (all bulbs not just one side) so I'm not sure how decisive that will be. There will be stamping on the case which will show the current and number of bulbs.

If your wiring looks standard then that's a great start. The slicing inside the looms is a real problem when tracing and I ended up unwrapping my looms but I was doing a major job and modifying everything.

Ahh that's a shame, I was hoping I had worked out a good test there, as im not sure how to test a 2 pin flasher without shorting it.
Unwrapping them is the only way sometimes, I would never have troubleshooted the heater issue without doing it. If i was thinking about using this car alot then a rewire would be best, but the wires themselves seem ok its just all the bad connections on the Datsun only parts like the switches.

 

[Rob Gaskin]

This is the blower cct.

Power should come from the air con fuse I think. HOWEVER I can now see on a diagram I have (Basic S30 USA) that power comes from the Accessory Relay (Red/Blue also supplies the HRW) then changes to Blue for the blower switch. This is what you have isn't it? I still say that the relay should be grounded by it's Black wire not the case.

 

[MaximG]

I found that this diagram was as close to my 72 240Z as any of them.

View attachment 47385

 

[PAR]

Hi Guys
I am following up on this post and I am also having difficulty finding a wiring diagram that matches my car which is a 73 uk car. I have an issue with the air con fuse blowing and didn't realise that it supplied power to the heater but must also supply another circuit as the fuse blows with the heater totally disconnected. All the diagrams I have seen don't mention the 2 fuse holder's as in the enclosed picture which a clearly original. I have also enclosed a picture of the rear loom wiring after the n/s/r lamp plug and need to determine what they are for ( I assume a couple would supply the antenna)