I'm working on a 79 5sp at the shop doing a variety of suspension stuff and another problem has presented itself.

Seems the car refuses to start. When I turn on the key, dash works, turn signals and hazards work, wipers wipe, but when the start button is pushed.. all I hear is a click (solenoid) but no start. Also, the headlights do not come up.

Some things I've done to troubleshoot:
Check battery and voltage (all good around 12.5 v at battery) and 12.5 at the jump post. I believe the battery is fairly new.
No draw on car that could be killing the battery.
Swapped in another starter to see if this would help (no change).

All fuses and relays are in their proper respective slots (fuses are good)..not sure on the relays but they are there.

So... Ignoring the "starter button" wired in (I know this could be part if not all of the issue but want to rule out other stuff first).. can someone walk me through the positive power pathway from the battery forward and maybe suggest some areas to look or other tests to do to cure this non-start ...

 

+12.5 at the jump post, starter clicks, sounds like ground issues, maybe block to chassis?

 

Tom,

it could be the relay you are hearing click.
Verify that the 14 pin plug has not come undone.
Also verify that you are getting +12V to the starter solenoid via the big yellow wire at the starter.

 

Grounds are good from block to engine.
The clicking is definitely outside the car..not at the panel...

The 14 pin is totally taped together..so not coming apart.
I will check the voltage at the starter solenoid (does this have to be when the push start is pressed...or will it be 12 V when the key is on)?

 

Terminal 50 - the 4mm wire on the starter is feed from the relay via the 14 pin connector, at pin 14. YES, the start button must be pressed.
When the starter solenoid pulls in, it provides 12v to the 0.4 ohm resistors and then to the coil and TIU.
If there is not enough current ( not volts, amps) to pull the solenoid in you will not start, even if it looks like you have 12 volts there. I would swap out relay XV and try again, maybe it has high resistance contacts. Otherwise, maybe time to pull the 14 pin apart and look for problems.
BTW, if you swap the wires on 16 and 50 it won't start either - BTDT!

 

try hitting the starter with a hammer if it starts after that it means the brushes in the starter are pretty much worn out and are sticking away from the armature, time for replacement or rebuild.

 

bat voltage 12-13 V at the big red stater wire, always.
12.5 volts at the small solenoid wire above the big wire when the button is pushed.
make sure the engine will turn by hand first.

Brad

 

Update...got back to it today.. Went looking for the starter relay..and there wasn't one.. This 79 is a manual so there is no relay (just a bridge).

I was able to check the voltage at the starter solenoid, and I've got just under 12 volts on the solenoid when I push the starter button.

This should be enough to get the starter to spin right? I've got 12 plus volts at the big connection on the starter and 12v on the small wire to the solenoid when the start button is pushed...

This is leading me to believe the starter is bad, but this is a second starter I've swapped in and has the same issue as the original one. I suppose both starters could be bad (I didn't test either starter yet)..

any more thoughts out there?

Regarding the current issue Neil.. could this be bad grounds?... I haven't cleaned them up yet..but they are not bad looking..

 

These might help:

http://www.nichols.nu/tip422.htm
http://www.nichols.nu/tip567.htm
http://www.nichols.nu/tip505.htm

Also, the fact that a 'start button' was installed leads me to suspect they had this problem:

http://www.nichols.nu/hotstart.jpg

 

Well the most obvious thing is to check for voltage at the starter solenoid (small connection) when the starter is active. If you have 12v there during starter operation then the starter solenoid is suspect.

However the fact that you have a "starter button" - is concerning in itself... why was that wired in, how was it wired in - e.g. is the relay even used now?

Alan

 

Thanks Randy.. I think I might just rig up that relay from the last tip...most direct way of getting power to the solenoid with little fuss..

 

Alan...this is a 79...no relay in the system at all (manual trans). It just has a bridge in place of the relay (where the Auto would have one).
The car worked fine until the battery died a while back. Ever since then, the owner couldn't get the starter to spin. He had it towed to the shop and I did a bunch of suspension stuff for him and am now looking at the starter issue.

Battery is fully charged, and the starter button does appear to function properly as I see 12V at the starter solenoid when the button is pushed (and 0 when not). There is also 12 V at the big connection on the starter.

I think the relay that Randy posted up will help "short circuit" the long wire that runs up at the 14pin connector and all the way back to the starter solenoid..and just use that circuit to activate the relay that will provide 12V from big connection on the starter..right to the solenoid...

 

I did that write-up after installing the fix on my previous '79 convertible.

Seems like many OBs suffer a similar malady.

 

The external starter solenoid that Randy refers to is to help increase voltage to the Solenoid on the starter.
The reason the early cars need it is because the large yellow wire in the front engine harness is junk and builds up lots of resistance.

If you replace this yellow lead, then you will no longer have a problem with the starter. However if you are pushing the button, and you have 12V there while pushed (as supposed to 10 or lower), then the resistance in the wire is not the problem and the problem is the solenoid on the starter. You may get lucky removing the solenoid and cleaning all points on it.