Electrical issue

[zureksmith]

I have a 1984 911 that will not turn over
Any suggestions ?
Turn the key and nothing happens just a click
all my lights , horn , radio etc is working
battery has a full charge ,terminals on the battery look good
just had the starter rebuilt and a new ignition switch installed just cleaned the ground strap on transmission to frame
what am i missing ?

[zureksmith]

I believe my problem is the connection of the yellow wire to the solenoid
does it travel from the battery (unfused ) to the ignition switch then directly to the starter ?

[spuggy]

Originally Posted by zureksmith

I believe my problem is the connection of the yellow wire to the solenoid

That would be a classic cause, yes.

Many, many things can cause the solenoid to simply "click" - including a tired/discharged battery, bad transmission ground strap (if it's green, it's junk), worn solenoid that sticks, or the grease gums it up. VW ones sometimes get too hot and do this (sometimes can free these off by tapping the solenoid).

I'd start by measuring voltage drop/current available at the yellow wire that connects to solenoid and proceed depending on what you find.

Possible the solenoid is just hung up somehow/dead spot inside etc; might try rotating the flywheel/tapping it etc.

Originally Posted by zureksmith

does it travel from the battery (unfused ) to the ignition switch then directly to the starter ?

Goes from the ignition switch (electrical portion of which can die without warning, or simply not pass enough current on some internal contact(s)), through a bulkhead connector in the cabin (might need cleaning/spreading contacts/re-seating) to the 14-pin connector on the engine bay fuse/relay panel (mine was awful inside - clean/spread/reseat etc if needed), into the engine harness and from there onto the solenoid connector.

[T77911S]

make sure the battery connections are also clean.

get a test light.
check it at the battery connection AT the starter.
then test the yellow wire at the starter.
you obviously need 2 people.
it should be very close to as bright as the battery connection

I would also check the light at the battery first.

[proporsche]

make sure you are connecting the yellow wire to the right connector at the strater..
Ivan

[zureksmith]

Hi
The car is starting now but not consistently some times it will just click when i turn the key
I believe my issue might be at the plug at the ignition switch???
I have tested the wiring from starter to 16 pin in engine compartment,and then from the 16 pin to the ignition switch plug all was good with multimeter.
I did installed a new ignition switch , so i am ruling that out for a while,took a look at the inside of the plug for the ignition switch all looks good ,anybody have any ideas??

just rebuilt starter ,new ignition switch, ground wires cleaned , good battery
and have tested wiring from starter to back of ignition switch with multimeter

[timmy2]

Clean up the male and female pins at the rear 14 pin connector. (Pin 1 in particular)
They tend to corrode or otherwise come loose.
May need to spread the male pins with a razor blade a little.

Have you checked at the solenoid wire on the starter to see if you are getting 12 vdc consistently with ever ignition key turn to start?
If you do, then you may have a bad starter solenoid with a worn spot causing the intermittent.

[timmy2]

Maybe spread the pins on the ignition switch harness at the 6 pin bulkhead connector too.

[LM3929]

I had the same problem, turned out to be the original ground cable, now I have a coupe of the electrical portion of the ignition switch if you need to try that out.

Lorne M.

[T77911S]

Originally Posted by zureksmith

Hi
The car is starting now but not consistently some times it will just click when i turn the key
I believe my issue might be at the plug at the ignition switch???
I have tested the wiring from starter to 16 pin in engine compartment,and then from the 16 pin to the ignition switch plug all was good with multimeter.
I did installed a new ignition switch , so i am ruling that out for a while,took a look at the inside of the plug for the ignition switch all looks good ,anybody have any ideas??

just rebuilt starter ,new ignition switch, ground wires cleaned , good battery
and have tested wiring from starter to back of ignition switch with multimeter

you CANT use a MM!!

a MM does not need any current to measure 12v. the solenoid NEEDS a LOT of current to pull in.
you need to use a test light. the light bulb requires current (not as much as the solenoid) to light to its full brightness. just compare to how the battery lights it up.

if the solenoid was not replaced its probably just a solenoid going bad.
the contacts inside get burned and build up resistance reducing the current to the motor

[boyt911sc]

You need a TL as suggested above if you want to diagnose and trace the anomaly. You could do this test solo. My TL has a 4-feet extension with alligator clips to do starter tests by myself.

Tony

[911pcars]

Confirm your battery post and all ground connections (including the gearbox-to-chassis ground strap) are clean and tight. We'll assume the battery is in a good state of charge.

Using a test lead or remote starter switch, bypass the switch by momentarily connecting the B+ battery wire on the starter to the solenoid terminal (yellow wire connection). If the starter motor now cranks consistently, the malfunction is upstream from the solenoid.

A test light can't measure voltage accurately. It merely lights up at a threshold voltage. You will want to measure the available source voltage when the ignition is in the start/crank position. When measured, the voltage should drop from 12V to approx. 7 volts, give or take.

AFAIK, there's no current spec at the yellow solenoid wire when cranking ( I suspect <10A). Typical MM have a 10A fuse protecting its circuits. Got spare fuses? If so, go ahead and try to measure the cranking current (MM in series, current (Amp) setting.

Voltage tests:
Disconnect the yellow wire at the starter solenoid, connect the MM + to it and the MM – to ground. With a helper (or long test leads), turn the ignition switch to the start/crank position. It should be close to source voltage (~12V). If not, use your MM to test for source voltage at all circuit connections at and between switch and solenoid.

Hope this helps,
Sherwood

[Joe Bob]

Whack it with a BFH. Then it should work.

[911pcars]

Originally Posted by Joe Bob

Whack it with a BFH. Then it should work.

I think (hope) you meant the starter motor housing rather than any body part. 🙂

Might be a decent option. Many Bosch starters were built with tight clearances. Engine heat can cause the armature and/or field coils to expand and create enough drag to prevent it from rotating.

Some techs spritz some water onto the starter housing to draw some heat from the unit.

[Joe Bob]

Tap the solenoid. Long time problem. Band aid fix is a Ford piggyback solenoid or replace the stock one if u can find a real German part.

[stlrj]

Call AAA. These guys see this all day every day and can get it started in no time with a quick cycle of the ignition switch. Happened to me and I was amazed how quickly they go it fired up.

A few weeks later a coworker got stuck and AAA blew his mind with the same magic...

[T77911S]

Originally Posted by 911pcars

Confirm your battery post and all ground connections (including the gearbox-to-chassis ground strap) are clean and tight. We'll assume the battery is in a good state of charge.

Using a test lead or remote starter switch, bypass the switch by momentarily connecting the B+ battery wire on the starter to the solenoid terminal (yellow wire connection). If the starter motor now cranks consistently, the malfunction is upstream from the solenoid.

A test light can't measure voltage accurately. It merely lights up at a threshold voltage. You will want to measure the available source voltage when the ignition is in the start/crank position. When measured, the voltage should drop from 12V to approx. 7 volts, give or take.

AFAIK, there's no current spec at the yellow solenoid wire when cranking ( I suspect <10A). Typical MM have a 10A fuse protecting its circuits. Got spare fuses? If so, go ahead and try to measure the cranking current (MM in series, current (Amp) setting.

Voltage tests:
Disconnect the yellow wire at the starter solenoid, connect the MM + to it and the MM – to ground. With a helper (or long test leads), turn the ignition switch to the start/crank position. It should be close to source voltage (~12V). If not, use your MM to test for source voltage at all circuit connections at and between switch and solenoid.

Hope this helps,
Sherwood

i did auto electric work for a living at one time and I am also an electronics tech (25+yrs). you cant use a MM. when I worked at a shop a MM was rarely used, by anyone there.

I have seen guys on here chase electrical problems with a MM and say they have 12v, only to find there is not enough current to operate the load.

[911pcars]

Originally Posted by T77911S

i did auto electric work for a living at one time and I am also an electronics tech (25+yrs). you cant use a MM. when I worked at a shop a MM was rarely used, by anyone there.

I have seen guys on here chase electrical problems with a MM and say they have 12v, only to find there is not enough current to operate the load.

What device did you use to check voltage?

Agree that a thin strand of electrical wire will still provide a 12V signal with a MM, and that alone is not enough to measure functional current carrying capacity.

However, in order for 12V loads to work properly, there must be a source for 12 volts, and that can be accurately measured with a MM, and only approximated with a test light.

An electrical load that normally requires 12V and X amount of current will attempt to draw that amount of current during operation. If the conductor path is compromised in any way that reduces that ability, a voltage drop will occur, and that can be measured.

Using a 12V test light on a modern electrical system with electronic sensors and components that operate at typically lower voltages can damage those components.

[T77911S]

you don't need to know voltage for something like this.

get a test light.
put it across the battery and note how bright it is.
then go to work on the car.
when my brothers 911 would not crank I did exactly what I told the OP to do.
I tested the battery cable AT the starter, then put the light on the yel wire while he cranked it. you could see a notable difference in the brightness. then I traced it back to a bad crimp (another one of my pet peeves) at the relay someone installed for an after market car alarm,.
by this time he had already replaced starter and ignition switch due to random no starts.
there may have been a voltage drop at the starter but I did not need to know how much, I new there was a problem.

you only need to know voltage if you suspect a bad battery or for alternator issues.

when I worked at the autoelctric shop, best one in Charleston sc, dealers even brought us cars they could not fix, I learned from guys that had been doing this for many years. I NEVER saw them use a MM for problems like this.
I even have a friend that has an electric shop here, when I have gone by his shop he is always using a test light.

you just don't need to know exact voltage for electrical work. its all about current. you HAVE to have the current to operate the load. I have seen SEVERAL guys on here working on lights that don't work. they measure 12v at the socket, they have good grounds, and people on here have them chasing their tail. if they had used a test light instead of a MM they would have fixed the problem much sooner.

put the MM's away and save them for battery problems or charging problems.