auto electric 101

[260 z]

I am refreshing my 260z and the electrical keeps kicking my butt.

I was blaming everything on the relays but weak grounds repeatably raises their ugly heads. Most of the wiring connections at the lights, gauges, and the dash are open so the car can go the the paint shop next. Could that be why I am not getting good grounds at some of the grounding point of the harness???? Could that also cause my wiper motor not to work from the combination switch??? Why do I get 10.4 volts on the harness side at the wiper motor connection when the battery is putting out 12.3 volts???

With the key on, and the combination switch at the

first position I read:

red lead LR wire LW and B read 10.4 volts

Y wire reads 9.94 volt descends to zero and starts over again.

Second position I read:

red lead LR wire B, LY, LW all read 10.4 volts

Y and L wires read 9.94 volts descends to zero and starts over again.

Third position I read:

red lead LR wire B and LW rear 10.4 volts

LY reads zero

LR and Y read 9.94 volts descend to zero and starts again

With the harness connection separated I get these rearing on the motor side:

42 ohms between the LR and W wires

5.6 ohms between the small B and both large B wires

continuity between the small B and Y

When I apply voltage directly from the battery 12.3 volts to the large black wires, the one makes the wipers go low speed and the other makes the wipers go high speed.

SURE COULD USE SOME HELP HERE

Edited April 3, 2011 by 260 z

[tlorber]

Wiring problems aside, while you are pulling the contacts apart, you should be spraying them with contact cleaner before reconnecting them. This will remove the oxidation and some of the resistance.

A slight voltage drop at each connection can add up to quite a bit at the end of the line.

Generally with electrical, you have to go bit by bit to rule out the good areas in order to isolate the problems.

[SteveJ]

Don't try to diagnose a lot when you're in the middle of another project. You can get confused easily. Get the car painted. Clean off the grounding areas well, and get everything connected. After that, let's see what you have.

[H4LIGHTS]

When you do get to the point of tackling the electrical another helpful hint is to use dielectric grease on all contacts and sockets.

Good anti-corrosion properties.

[Dobber]

Have to use that product sparingly ( dielectric grease ) as it is non conducting and can actually cause resistance.

[EScanlon]

Good point Dobber.

Dielectric grease by itself does not create or improve a poor connection, what it does is stop it from corroding, but it must first be a good mechanical connection.

E

[260 z]

The reason I was trying to get the wiper motor operating correctly prior to painting was so I would not have worry about the paint getting scratched.

With a lot of the connections opened, is that why my voltage is low, I'm I chasing a ghost ?

[EScanlon]

Before you actuate the wiper motor, and before you mount the arms, put a small "flag" of tape on the wiper pivots and then actuate the motor. If you've installed the linkage wrong, it can only be in one of two positions, the wipers would wipe DOWN first, before cycling back up. If you've used the tape, you'll be able to see that and can then r&r the linkage 180° off from what you had.

The wiper motor, if it's operating properly, will have "parked" itself and therefore it "thinks" the wipers are at the bottom of the screen because that is the "Park" position. Only if you've actuated the motor and NOT let it cycle through to the PARK position would this not be correct (presuming you didn't open up the gear case and move things around).

FWIW

E

[lmcguffin]

The power to operate the wipers and other accessories is switched with the Ignition key switch. Over time these contacts degrade and will develop resistance (causing heat). Heat further degrades the contacts, so it's a progressive erosion. Check the voltage on the power to the switch (should be large white/red wire) and the voltage on the power to the accessories fuses (I believe a blue/red wire) and see how much voltage drop is at the key switch. Also check the fuse contacts at the fuse clips in the fusebox.

Inspect the various male/female connectors around the steering column for signs of contact heat damage (usually a discoloration in the plastic).

The contacts on the key switch are somewhat sealed, but you might have some luck with an electronic contact cleaner followed by a good quality electrical lubricant (CRC 2-26) that is forced into the contact block.

The key switch on my 260 was causing several problems due to voltage drop.

[260 z]

Mechanically the wiper are OK. If I connect a wire directly from the positive of the battery to either of the large black wires coming from the motor, the wipers go back and forward on high and low speed.

The voltage coming out of the wiring harness is on the Blue/ Red wire ??? Could my problem be a relay that is mounted on the wiper motor and NOT permitting the voltage from the wiring harness get to the motor????

[ZCurves]

Mechanically the wiper are OK. If I connect a wire directly from the positive of the battery to either of the large black wires coming from the motor, the wipers go back and forward on high and low speed.

The voltage coming out of the wiring harness is on the Blue/ Red wire ??? Could my problem be a relay that is mounted on the wiper motor and NOT permitting the voltage from the wiring harness get to the motor????

Do you have access to a wiring diagram for your 260? I bought a color wiring diagram for my '78 from Prospero's Garage, it has helped me very much. Do you have any spares of the various relays so that you could compare their operation.

Having been in this situation before, I think that if you can study the wiring diagram first and isolate the components for that system, then it is a matter of eliminating the variables. Like SteveJ mentioned before, get the grounds handled first. Then check and clean all of the Fuses - if they are old then discard and replace with new ones. Clean the contacts in the Fuse Block. I encourage you to clean the Combination Switch (take apart) I bet this is where your problem is.

Tip: After you lick the wiper issue, buy some braided ground straps and place one from the ECU to the Body and another from the Engine to the Body.

I live in Spring - if you want to get together for a closer look, PM me.

[lmcguffin]

The blue/red wire at the key switch is power to the group of fuses noted as "Accessories" in the fuse box.

The wiper system is easily the most complex control scheme in the entire car...there are relays in the wiper motor assembly in addition to the intermittant amplifier that controls the "Int" position. As noted above, the wipers have power when the Combo switch is in the "off" position so that they can reverse and park. The is a limit switch on the wiper gear box that stops the motor when parked, and then sets up the wiper to operate when switched on again.

As also noted above: Check the combo switch, fuses, and connectors at the intermittant amp (in passenger footwell under dash), and wiper motor.

You may then have to start replacing components.