Starter relays different for Auto and Manual transmission?

bronze turbine

Active Member
Joined
Apr 26, 2019
Messages
338
Reaction score
348
Location
Berwick, PA
So, we took the '68 300 out for a drive today, and almost got stranded because when we tried to start it after it was parked for a while, the engine wouldn't turn over. My brother tapped on the starter relay a bit then it turned over. So, I figured we'll get a new starter relay, they're cheap, and we can at least be sure that part is good. Now here's the thing....there's 2 different starter relays depending on whether the car has a manual or an auto trans. This car was originally an auto, of course, but has been converted to manual. I don't know what the difference is between the 2 different relays, so I'm not sure if I need the one for manual trans now or should still install the one the car came from the factory with.
 
So, we took the '68 300 out for a drive today, and almost got stranded because when we tried to start it after it was parked for a while, the engine wouldn't turn over. My brother tapped on the starter relay a bit then it turned over. So, I figured we'll get a new starter relay, they're cheap, and we can at least be sure that part is good. Now here's the thing....there's 2 different starter relays depending on whether the car has a manual or an auto trans. This car was originally an auto, of course, but has been converted to manual. I don't know what the difference is between the 2 different relays, so I'm not sure if I need the one for manual trans now or should still install the one the car came from the factory with.

Check you current relay, the automatic relay has four terminals, most of the manual transmissions had three. These relays are famous for having the terminals corrode and the wire connectors getting loose enough that they did not make contact. Clean it up and it will probably still work. Most of the after market relays are China crap and won't last.

Dave
 
Is the 4th wire connected to the neutral safety switch circuit somehow?

When the car was converted to manual transmission, was the factory wiring changed at the starter relay? Just curious. OR was something, some where else left disconnected, which might have connected to the starter relay?

DO clean the battery terminals. I found out, from experience, that even if they look "good", there can still be a thin layer of corrosion between the terminal and cable end. Cleaned the terminal and then "starts" happened as desired.

ALSO, check the integrity of the connection of "the big red wire" that comes through the bulkhead connector and goes to the ignition switch. On both sides of the bulkhead connector. Had that problem, too.

Just some thoughts,
CBODY67
 
The auto starter relay has a terminal for the neutral start switch. The manual does not. You can use the auto relay however by wiring the neutral switch to ground. That fools the relay into thinking that the car is in park and allows it to start.
 
So, would that also mean that later models, with the clutch-start switch. would have 4-prong relays, too? Just curious.

Thanks,
CBODY67
 
I looked at the wiring diagrams as well as pictures of both types of relays and I found that the only difference is that on the ones for manual transmission the terminal that goes to the neutral safety switch on the transmission is grounded to the chassis. It seems logical that you could somehow hook up a clutch pedal safety switch to that same terminal, but as far as I know '68 c-bodies didn't have one.
I'm going to check/clean all the terminals on the relay, the bulkhead connector, and the ignition switch first though as suggested before I replace anything.
 
Not rocket surgery....

Manual trans relay Note the terminal in the corner is missing and in its place is a flat section soldered to the case. That provided ground.

691-2095609.jpg


Automatic

s-l640.jpg
 
This is all fixed. The ground wire that was added to the starter relay because of the missing neutral switch was not properly attached. Thanks everybody!
 
Back
Top