Toms cutlass

'70 Cutlass Conv't. power seat feed wire. Which location on the fuse box does the seat feed wire plug in to? The ASM shows: "ACCSY" is for electric windows and vanity mirror lamp (20 amp fused); "BAT" is for headlamp off delay control; and "IGN" is for cruise control feed. The seats are not fused, but may be regulated by a 40 amp circuit breaker along with the power conv't. top (breaker mounted on the firewall in the engine bay).

I'm pretty sure BAT is the correct location for the power seat feed connection.

Thanks in advance.

rocketraider

You need a copy of CSM with wiring diagram which assembly manual doesn't have. It will show the wiring from junction block and ignition switch to fuse block and power distribution thru the individual fuses and power taps. Fisher Body Manual will have power window and seat wiring diagrams.

Sometimes a fuse block will have cavities marked as to what accessory plugs in where but don't see that on yours.

Toms cutlass

Thanks for your reply. I did check the Chassis & Body Service Manuals too. Lots of detail of course, but it pertains to the seats; not the power feed connection at the fuse box. Other diagrams show fuse box detail, but not the power seats feed connection. Manuals confirmed circuit breaker (40 amp) on the firewall engine bay side for "electric seats and power top."

4speed455

My car is a convertible with power windows and power seat. With that combination there is a circuit breaker on the firewall that supplies power to a power accessory junction under the dash. My power window harness and top switch are plugged into that junction. The power window harness has a power wire built into it for the seat. If you didn’t have power windows you could run the seat wire directly to that power accessory junction if present or directly to the circuit breaker.

Toms cutlass

Thanks, I appreciate your reply.

My conv't. top switch is wired through the circuit breaker (40 amp - not a fuse) on the engine bay side of the firewall which runs to the battery. If I connect the power seat feed (orange with black stripe wire in the image I posted) to the Accessory post on the junction box, it will blow that 20A Accessory power fuse. Like the conv't. top, the seat motor draws more than 20A and so must run through a circuit breaker, not the junction/fuse block. All of my harnesses are OE or OE replacement. The orange power seat feed wire is correct; it runs alongside the intermediate wire harness under the carpet to the rear and connects under the driver's seat to the power seat motor, exiting from under the carpet at the split between front and rear carpet pieces. Given the relatively short length of that power seat feed wire, I know it plugs into the junction block - either the BAT or IGN post. There are no connectors in my dash/main harness for a power seat, which as you know, is a heavy gauge wire to handle the higher current draw.

I added the power seat option many years ago, and without verification to any manual, connected it to the "BAT" terminal post on the junction block. It's worked fine, but now that I have all of the correct wire harnesses, was hoping to confirm that it should in fact be connected to the BAT and not the IGN terminal.

Another way of asking: Should the power seat work without the key in the ignition?

4speed455

Sorry I wasn’t clear the accessory junction I was referring to is not on the fuse panel it is connected directly to the circuit breaker, goes through the firewall and can have three power accessories plugged in to it.



https://www.opgi.com/ignition-electr...con-36861.html

4speed455

Also to answer the other question, yes it should work without the key. Even in my power window/power seat harness which is OEM, the windows run off a relay which only has power with the key on, but the power seat feed does not run through that relay so it always has power.

joe_padavano

Actually, what he needs is the Fisher Body Manual. Wiring diagrams for body accessories like power seats and power windows are in the FBM.

Toms cutlass

I appreciate all of your replies.

I re-reviewed the Fisher Body Manual (FBM) and Chassis Service Manual and find nothing about where the power seat power feed wire connects on the fuse box, under dash harness, or other.

Under "Seats" for power seats, it states: "The seat adjusters are actuated by a 12-volt, reversible, shunt wound motor with a built-in circuit breaker." If the power seat motor has its own circuit breaker, there would be no need to have the power feed for the seat run through the 40 amp circuit breaker in the engine compartment side of the firewall (under the brake booster). The power feed wire could plug directly into the "BAT" connector on the fuse box and be protected by its own internal circuit breaker.

However, under the "Introduction" subsection of "Electrical" in the FBM it states: "Circuit wiring for all power equipment is protected by a 40 ampere circuit breaker ... . A 'bolt-on' circuit breaker is used by Chevrolet and Oldsmobile and is located on the engine compartment bulkhead." (See image of circuit breaker below.) My power conv't. top power feed wire is connected to that 40 amp circuit breaker via the harness in the image below. 4speed455, do you have two power feed wires running to the 40 amp circuit breaker on the firewall engine compartment side, one for your power top and one for your power windows and power seat using the accessory harness shown in your post?

4speed455

My top switch was bypassed so the harness was hacked and I added the power windows and seats, so I can’t say how it was originally. Currently I have only one wire coming off the circuit breaker feeding that junction under the dash. My top switch and power window/seat harness are both plugged into the junction. My guess would be two wires would run through the firewall from the factory. I doubt they made two different switch harness one for cars with other power accessories and one with out. I bet every convertible left the factory with the wire connected directly to the circuit break and if you had other power accessories the junction wire would be connected the breaker too.

joe_padavano

The internal breaker protects the motor. It doesn't protect the high current wires leading TO the motor, which are more likely to get knicked and short out. The fuse box is NOT wired to support a 40 amp load. The high current power accessories all run feed wires from the threaded post on the horn relay, and are protected by a circuit breaker under the hood.

Toms cutlass

4speed455 and Joe, you've both been very helpful.

Point well-taken, Joe. Confirms 4speed455's comment regarding the 3-way power feed accessory harness (image posted above) for multiple power accessories connected to the 40 amp circuit breaker.

That 3-way feed power accessory harness is listed for the A-Body Chevy (Chevelle, Monte Carlo) only. I checked and confirmed with M&H Electric as well. However, there's a similar power feed accessory harness (#28215) shown for only one (1) power accessory connection. (See image.) Again, listed only for A-body Chevy not Olds, but the description for the power seat feed wire (#14175) (connected at the seat motor running under the carpet to the junction box area) states in the M&H catalog that it should be connected to either the single or 3-way power accessory feed harness which is connected to the circuit breaker!

I'm going to pickup that harness for connection from the circuit breaker to the power seat feed. That way, the power seats and power conv't. top each run through the 40 amp circuit breaker.

Thank you again, really appreciate your guidance.

Toms cutlass

Update: Installed the single feed power accessory harness (#28215) connecting to the same post on the 40 amp circuit breaker as the power top accessory feed wire. Ran the power feed through one of the holes in the OE 3-hole firewall grommet (one hole for the tach wire, one for the power top feed wire, and now one for the power seat feed wire). Works perfectly and now have peace of mind that the power seat and wire harness are protected by the firewall circuit breaker.

Thanks again 4speed455 and Joe.

Note: I removed the grommet that was pre-installed on the power feed accessory wire as it was not needed.