I am new to this forum and to the car. A good friend of mine just bought a restored or close to restored 1968 Cutlass S Convertable 350 3 speed auto. It has a few issues yet but the biggest one is the electrical. The bearings in the alternator were making noise, so we replaced it. The battery was also replaced at the same time. Well now that we did this, the whole electrical system is dead, no lights, no starter click or anything. It ran into the garage to fix it, it is 10 degrees here, the car is not driven in winter but after...nothing. Now we looked at the ground wire and the area that it is attached to is all powder coat...no bare metal...would that cause a problem. The car did have a dead spell where nothing would light up etc when we bought it but it was able to be jumpstarted and it ran...figured the battery was low from sitting. This time the jumpstarting didn't work....so dilemma. So, sorry for the long post...if anyone knows anything about these cars....please reply. Thanks for any help you may be able to offer. The car came out of the Mecum Auto Auction last week in Kissimmee, FL. Now it is living in Northern Wisconsin! What a shock for it! Maybe it is rebelling!

 

I would check the fusible link. I believe its a thick wire that runs from the horn relay junction to the fuse box. Just my guess, others may elaborate a bit more.

 

The first and most obvious solution, especially if you plan to keep the car, is to buy a 1968 Oldsmobile Chassis Service Manual- the one the factory produced and the dealer service techs used. It will have a complete electrical troubleshooting and repair section that includes a full-color wiring diagram.

On a V8 68 Cutlass, there should be a 10 gage wire from the (+) battery post to the horn relay/junction block on the fender. Check to see that it is there and has good connection at both ends. If it does, there are two other RED 12 gage wires attached to the relay post. One of those goes to the alternator output post; the other supplies the car's electrical system. That one will have a short section of black or red wire in it which is the fusible link. If the fuse link is broken, burnt out or corroded, nothing electrical on the car will work.

If this was originally a 6-cylinder car that got changed to V8, the wiring is a little different and the fuse link will be at the starter.

Grounds should have a good clean connection, though I would think that even with powdercoat the ground would establish thru the ground bolt threads. The battery (-) cable should ground to the engine block. There should be a short length of 12 gage wire from the battery (-) cable attached to the radiator core support. There should also be a braided ground strap from the rear of the engine to the firewall. You might also find other ground straps thruout the car.

 

Thanks both of you for your information, I will be working on the car this weekend. I will be checking the fusible link. Thanks for describing the location rocketraider. I do have a wiring schematic of the whole car from a FSM. The car has the original 350, it was a two-barrel engine now it is a four-barrel engine. Original A/C too. Will be a good cruiser once we get some warm weather....which doesn't come until May or June

 

The car will be around for a while too so will be investing in an FSM. Any places that you recommend buying one from?

 

Turned out it was a wire splice from the positive battery post to the junction block on the fender that was not bad. Put the volt meter on it and was showing some voltage spikes meaning 0-12.74 volts when moving the wire. So put a new crimp on the wire and it's good to go. Thanks for all your help. The crimp is about 5 inches from the battery, I have to wonder though if their was suppose to be an inline fuse there? Goes from a black wire out of the battery to a 10 inch red wire to the junction block on the fender. At least it is running now...Have 2 months before the roads are clean of snow and salt yet! Thanks!

 

For future reference, a voltmeter won't always show a bad or high resistance connection. A test light is a better device for this, since the light bulb provides a load that will find a high resistance connection.