No start & electrical issues

[grnsky]

Really need some electrical help in trying to revive the '71, I've uncovered a host of electrical issues that seems unmatched on the forums.

Car has been sitting for 4 years. But is stock, and has no electrical mods that I can see.

Heres what I have (with a good battery)

-Emergency flashers

-Brake lights

-Parking lights

-Washer bottle motor;)

-Wipers

-heater

Heres what I dont:

- No start, no starter engagement -No power getting to starter solenoid lead when trying to crank (read by my friend with a voltmeter). Just get a clicking from the accessory cut out box in the passenger footwell.

- No dash lights

- No headlights

Have swapped out fuse box, ignition tumbler, acc. box, to no avail.

Seat belt alarm is constantly on when the wires from ignition are connected also.

Any ideas would be great. Fuesable links? Wires seem in good shape, as I looked around for any rat damage, not much corrosion on the terminals either.

Starter motor is also good and rotates when I arc it, so have a free spinning engine which is a relief!

[kenz240z]

Time to break out the continuity tester and the DVM. For the no start situation, remove the starter lead from the solenoid and connect the continuity tester to it. Clamp the other end of the CT to a good ground. Turn the key and see if the CT lights up. If not, test the ignition switch itself. I can't recall which pin on the back of the switch goes to the starter, refer to the FSM.

Not sure about the lack of dash lights or head lights. Test the fuses with a DVM. A bad fuse can look good to the eye. Also, make sure your grounds are good and all connectors are free of corrosion and tightly connected.

[Zs-ondabrain]

If you have parking lights but no dash lights, then the dimmer is likely the problem (located under the dash on the tach side of the column)

No headlights is likely the fuses, or associated wires from the fusebox (being that you swapped boxes) or start checking the switch and wires in that area.

I'd also be inclined to start looking in the passenger side area for unplugged connectors.

[SuckSqueezeBangBlow]

There's gremlins in there I swear.

Anyway, I've been helping old boy here with all things Z related lately, and did some electrical trouble shooting on the '71 yesterday. First, the starter works, jumped the signal wire on the solenoid and everything turned over fine. The ignition switch is operating correctly as well, verified by a brand new switch swapped in for this exact purpose. We installed a known working fuse box as well. The problem seems to be in the start circuit, between the switch and the starter motor. The coil has power in the ignition switch "on" position.

Anyone know for sure if there is a start relay somewhere in this circuit. What I really need is a better wiring diagram to diagnose this properly.

[Zs-ondabrain]

http://www.xenons30.com/files/1971%20FSM%20Supplement.pdf

Here's a PDF of the 71's Sevice manual, it includes wiring diagrams and everything else.

Scroll all the way down for the basic and late 240Z wiring diagram (literally last 2 pages.

Here's the main site......

http://www.xenons30.com/reference.html

Edited January 6, 2011 by Zs-ondabrain

[Zed Head]

SSBB, any chance you could change your screen name? It's really unpleasant to look at.

Not even sure why someone would do that...

[SteveJ]

SSBB, any chance you could change your screen name? It's really unpleasant to look at.

Not even sure why someone would do that...

What? Don't you like internal combustion?

[Zed Head]

Yeah, I know, but this just doesn't seem like the right place for that kind of innuendo. I'm trying to focus on cars here!

[grnsky]

Right.......

Getting back to it, I changed the fuses out today with no change.

Also dont think its a dash dimming problem as I have no dash brake light, nor any of the gauges respond when key is in the on position.

Any other ideas?

[Zs-ondabrain]

it IS the rheostat (dash light dimmer). The dash located Brake light has nothing to do with the dash lights. The parking light circuit controls the dash lights (illumination) the sidemarkers, front marker lights and taillights.

The brake light on the speedo is activated by the E-brake handle switch and/or the low pressure switch located on the distribution block below the master cylinder.

As for things not lighting or operating apon the ignition switch being turned on, I would start looking at the actual ignition switch wiring, then the fusebox again and the dash connections locvated on the passenger side under dash area.

Those are my 25 years worth of "Other ideas"

Dave

[SuckSqueezeBangBlow]

http://www.xenons30.com/files/1971%20FSM%20Supplement.pdf

Here's a PDF of the 71's Sevice manual, it includes wiring diagrams and everything else.

Scroll all the way down for the basic and late 240Z wiring diagram (literally last 2 pages.

Here's the main site......

http://www.xenons30.com/reference.html

Thanks for that. That diagram is hard as hell to follow though. We were looking at an original print FSM when working on the car. I like the diagram in the chilton book way better though. (didnt have it at the time) Its alot easier to follow for practical diagnostics.

[SteveJ]

Yes, it takes a little effort to trace the wires on the FSM diagram, but it's more accurate as far as wire colors go. For true diagnostics, accuracy is better.

The start circuit is rather simple. Look at the grid above IGN. SW. This grid shows you what contacts are made for each key position. The top line is for the Accessory position. The second line is Off. The third line is Run, and the last line is Start.

The W/R wire is the 12VDC+ coming into the switch. When the key is in the start position, the B/Y and G/L wires should have voltage. The B/Y wire goes to the solenoid. The G/L goes to the ignition circuit (and bypasses the ballast resistor). That means you should have 12VDC at the coil when the key is in start.

When the key is in the run position, the B/W and L/R wires have voltage. The B/W wire passes through the ballast resistor and powers the ignition. The L/R energizes the accessory relay and powers other key-switched circuits.

The running/parking lights are powered through the headlight switch. The G/L wire carries the voltage in, and the G/W wire carries teh voltage out. The G/W wires branches off to the rheostat to power the dash lights, too. I believe it's an R/L wire going to the dash lights from the rheostat.

The headlight circuit is unique. The W/R wire carries 12VDC+ to the fuses for the left and right headlights. There is a R/Y wire for the left headlight and R wire for the right headlight. From the headlights, the R/W and R/B wires return to the Turn Signal switch. If you select low beams, the R/W wire will be connected back to the headlight switch. If you select high beams, the R/B wire will be connected back to the headlight switch. When you turn the headlight switch on, the ground is connected to complete the circuit, allowing the headlights to come on.

As Dave said, check the connectors, and check that you have the circuit connected for the ground path between the turn signal and headlight switch.

By the way, Dave makes highly regarded relay setups for the headlights and parking lights and sells them through Motorsport Auto. They do a lot to relieve the stress on the 40 year old wiring. If you don't want to do the parking light relays, then consider swapping out the parking light bulbs for LED bulbs. They dramatically drop the current flowing through the circuit.