View Full Version : Overdrive Fuse Blows

11-21-2004, 09:54 PM
Have a 1952 Champ 6 cyl., 3 speed , overdrive. All of a sudden , this weekend, the overdrive quit engaging. Checked it out and found Relay Fuse blown. (the firwall mounted relay for overdrive)

Put another fuse in, it blows as soon as you turn on the key. Anybody got any idea's ?

11-22-2004, 11:17 AM
Well, It could be the solenoid's gone belly up but I'd be looking at the wiring for a short, first. If your '52's wiring is original, it may have finally chafed thru the power wire somewhere. Try taking the two leads loose from the solenoid and then installing another fuse. If it still blows, it's not the solenoid. If it doesn't blow, then there's a good chance it IS the solenoid is shorted internally.
And even IF the main harness is new, it could be that the OD harness wasn't summarily replaced when the main one was (I've seen such a scenario). Lotsa vibration goin' on there where the OD wiring runs down to the solenoid. Easy to envision a short developing.[xx(]

Miscreant at large.

11-28-2004, 08:16 PM
You were correct, Mr. Biggs. The overdrive solenoid is the problem. The post that the large red wire goes to from the relay is shorted to ground. I took the solenoid apart to look for reason the windings or something inside would be touching the case of the thing, but, I have to tell you the naked eye seen nothing. If you put an ohm meter from the red wire connection screw hole to the case it reads straight through. Trouble must be in its inards somewhere. Well, now I know the problem, but, what caused it? and where in the world do I get another one?

11-28-2004, 11:03 PM
Not so fast.... Reading that terminal to ground will give you a reading of practically zero ohms. Did you try reading the wire to that terminal to ground? With it disconnected from the solenoid, of course.

Miscreant at large.

11-29-2004, 07:49 PM
Thanks for the come back Mr. Biggs. Give me awhile on that recheck. Unfortunatly, I only get to work on Stude. on weekends.

The best I could tell, the insides of the solenoid are shorted (grounded) to the case. With the solenoid on the bench , and , using an ohm meter , I check across from red wire terminal to the case and meter reads through. On the other terminal it reads across ok, (meter does not move).

I will recheck things and let you know.

12-06-2004, 03:31 AM
I'm in agreement with Mr. Biggs on this. An ohm-meter check on the large terminal may be misleading because the pull-in winding of the solenoid has a very low resistance when it's good.

Can I suggest you "bench-check" the solenoid. Easily done with a pair of jumper cables, using the car's battery. Connect one cable from engine block to the case of the solenoid. Clamp another on the battery negative terminal, and touch it momentarily to the large terminal on the solenoid. The solenoid should extend instantly, and there will be a small spark as you make and break contact. If you get a BIG spark, and the solenoid does not extend, it's shorted. I would expect a shorted solenoid to have a BAD burnt odor if you open the case.

The solenoid has two windings in it, with an internal switch. In the rest position, the internal switch connects the large terminal to the low-resistance "pull-in" winding. When the stem is fully extended, the internal switch disconnects the "pull-in" winding, leaving the high-resistance "hold-in" winding in the circuit. If the internal switch is bad, that could cause the fuse to blow, as I expect the current draw of the pull-in winding would not blow the fuse as a momentary load, but would if left on continuously. Likewise, a mechanical fault with the overdrive pawl could be preventing the solenoid from extending fully and un-switching the pull-in winding.

Hope this helps,

Gord Richmond, within Weasel range of the Alberta Badlands

12-06-2004, 09:41 PM
Put another fuse in, it blows as soon as you turn on the key. Anybody got any idea's ?

Some how men I'm confussed again. Is not that fuss on the relay not doing any thing till the relay engages? Or is that fuss protecting the winding of the relay? The part about it blows as soon as he turns the key on, is borthing me.


12-07-2004, 11:28 AM
I just went through this in my '60 Lark. It doesn't have a relay, but the wiring is similar.

The hot wire, downstream from the fuse, (it doesn't even go through the ignition in my Lark) energizes the solenoid when the ground is made.

The ground is made by the governor reaching it's energize speed. Or by a short in the wire between the governor and the solenoid

To test this wire, disconnect it from the solenoid and put a fuse in, or check for continuity in the power feed.

Tom Bredehoft
'53 Commander Coupe
'60 Lark VI

12-07-2004, 03:11 PM
Railway (Ebon) that's why I mentioned the old wiring of this '52. The guy hasn't said if it's got the original wiring in it. If it did, I'd be afraid to drive it anywhere!
There could be a short in the circuit that carries the "ground" to the relay or even have a bad relay![V]

Miscreant at large.

12-07-2004, 05:51 PM
Yaall, now I see. The relay is always engaged. And another short down the line. Thanks Mr. Biggs that cleared up the muddy water for me.


12-15-2004, 07:32 PM
Just remember that is is really a simple circuit, with a couple of ground sources.

I had a similar experience last summer.
I had blown fuses and a non working solenoid.
But when I jumpered the solenoid it worked ok.
Checked and re-checked everything in between brewskies...
Was about ready to rewire the whole thing when a moment of sanity overwhelmed my 'tear it out' senses.

Checked the circuit against the OEM diagram to be double sure a wire wasn't out of place.

Took the relay off the firewall and pried off the sheet metal cover.
Took a point file (NOT emery paper or sandpaper) and cleaned the contacts. Put the cover back on. There is a piece of paper wrapped around the wiring coil in there and it looked like there was a spot something was touching. I flipped the paper over and put the seam on the other side.

All of a sudden, the O/D started to work like it was 1956 all over again. I had a happy customer (who was quite inebriated, and amazed all at once <lol>)

It is AMAZING to drive an O/D equipped Stude when compared to a straight 3 speed... AMAZING!:D

'61 Hawk
'37 Coupe Express

01-06-2005, 09:56 PM
The Holidays are over and time to get back to whats really important. Goin to the shop this weekend and try to solve the fuse blows when overdrive is engaged.
Thanks for all the input guys. I printed it all off and will use as notes as I check things out. I have allready installed all new wiring and I kinda think I might have dinked something up somewere, so I plan to recheck everything. When I solve this, will post what I found so it may help somebody else out.
Have contacted Cathcart about conversion to 5 speed S-10. I may go that way if I can't solve this thing. Will keep you informed.