Power Seats on 87 Suburban

[Tx_Phil]

Does anyone know if 87 Suburbans came with a power seat option?  I would think so but from the wiring diagrams I have I've not see this addressed. 

I am asking because my 87 Suburban has a set of "Good Times" conversion power seats (driver & passenger) which were none functional when I got the truck.  I traced the wiring back to what looks like an after market fuse block which had no power source.  I used a jumper with an inline breaker to test the seats and found the driver seat to be working but the passenger had a dead short.  The wiring harness for the seat was pinched and welded to the seat frame.  I repaired the wiring and the passenger seat work properly now as well.

My question is how should I power these seats?  What is the proper way to do it? 
I've not found any opening on the factory fuse panel so I'm guess that might not be an option.
I could reuse the after market fuse panel but I'm note sure from where I should draw the source power to energize the fuse block?

A few pictures of the after market fuse block
The orange and brown wires are the ones going to the power seats.


Note the empty terminal below the orange and brown wires.  I think this is where the source power should go, right?  Oh, and no I have no idea where all of the other wires are going to but none of then are energized with the key on or off.




The factory fuse block \ panel

[zieg85]

To my knowledge our style trucks did not offer a power seat option but I've been wrong before

[Tx_Phil]

That makes sense considering I've not found anything referencing power seats in the wiring diagrams.

[blazing816]

I would be concerned with the aftermarket fuse panned looks like something is burnt....and one fuse is only 7.5amps which is really low of autos....10 is even (not so much on our trucks) I just would wire them straight to a constant power source so u can move them with truck off to make it easier to get in and out if necessary

[bd]

Opinion:
Your 'thumb' is resting on the red power supply wire (1st image).  It appears to be either 12 or 10 gauge.  What's the capacity of the two circuit breakers that feed the seat motors - 30 amps? 

So as not to overburden the factory cab wiring:  if the red power supply wire is 12 gauge and the breakers are no more than 25 amps each, I might extend the red power lead through a grommet in the firewall (or a bulkhead feed-through - 2nd image) and attach it directly to the firewall junction block through a six-inch length of 16-gauge fusible wire with butt and ring terminals securely crimped, soldered and shrink-sealed.  If the red power lead is 10 gauge and/or the circuit breakers are 30 amps, I would still feed it through the firewall, but I would be inclined to run the power lead to a protected junction block mounted near the battery, using a six-inch length of 14-gauge fusible wire securely crimped and soldered (3rd & 4th images). 

[Tx_Phil]

I would be concerned with the aftermarket fuse panned looks like something is burnt....and one fuse is only 7.5amps which is really low of autos....10 is even (not so much on our trucks) I just would wire them straight to a constant power source so u can move them with truck off to make it easier to get in and out if necessary

What you see in that picture that looks burn and rusted is the breaker to the passenger seat which had the dead short.  I believe the PO tried to get that seat to work several times without trying to find the root of the problem. The wiring from the 8-way control panel on the seat was pinched when someone put the seat all the way down. The wires were all melted together (copper melted, not just the jackets) and it was basically tack welded to the seat track.  I was really surprised when the seat motors worked after repairing the wires.

Yes, there are several really light duty fuses in there.  I really think one of the POs either added accessories or this truck went through a conversion process.  There seems to be a whole lot of wire that really go no where. There is an after market CD player, an FM signal booster and someone tried to mount 6x9 speakers in the doors. They stopped 1/2 way after sawing into the power window motor!

[Tx_Phil]

Opinion:
Your 'thumb' is resting on the red power supply wire (1st image).  It appears to be either 12 or 10 gauge.  What's the capacity of the two circuit breakers that feed the seat motors - 30 amps? 

So as not to overburden the factory cab wiring:  if the red power supply wire is 12 gauge and the breakers are no more than 25 amps each, I might extend the red power lead through a grommet in the firewall (or a bulkhead feed-through - 2nd image) and attach it directly to the firewall junction block through a six-inch length of 16-gauge fusible wire with butt and ring terminals securely crimped, soldered and shrink-sealed.  If the red power lead is 10 gauge and/or the circuit breakers are 30 amps, I would still feed it through the firewall, but I would be inclined to run the power lead to a protected junction block mounted near the battery, using a six-inch length of 14-gauge fusible wire securely crimped and soldered (3rd & 4th images).

Thanks for the feedback, this is helpful.

Yes sir, I believe you are correct.  The red wire under my thumb "was" the power source but that wire has been cut and I've not found the other end yet.  You can see that same red wire in the other pictures and it's only about 2-3 inches long.


I like the idea of going through the firewall to the terminal block on the firewall.  My thought was to jumper from the factory terminal block to a new terminal block and then through the firewall to the fuse block.  I plan to mount some driving lights \ work lights on the rear of the truck so I thought adding a new terminal block and using it for all of my connections might be a good idea.  I had not thought about using a fusible link between the two terminal blocks.  I like that idea.  Would a fusible link or an inline circuit breaker be better?

If I am following along correctly, the reason for coming directly off the battery to a new terminal block is to protect the lead from the battery to the factory terminal block on the firewall.  Since I plan to add at least a couple more electrical load items do you think it best to just take this approach now so it's ready when I add items later?

I believe the circuit breakers for the seats are 30 amp but I will need to double check. The work lights will be 55watts so that should be 10amps for both of them. I would expect to see a max of 40 amps in the terminal block if both lights are on and one of the seats is moved at the same time.  Not likely but it's possible.

[blazing816]

With the seat to me it sounds like you would be better off starting from stratch. I would run an inline fuse wire off a constant power source and you can use a distrubution block or just run a 60amp inline fuse and thicker wire to run both and power the seat from that and get rid of that whole seperate fuse block. Just also make sure that the seats are ground to a good ground. Rusty grounds are not very reliable. Unless I am not understanding right and that little black box with the fuses is what is built into the seat to make it going in all the different positions??

With work lights what I do is use a 30amp relay (pre set of lights) and a fusible link. Because work/off-road light ussually need a good power source, the best thing to do is run a wire straight from battery to realy, and then run a keyed power wire (and I brake that with a swtich) to relay and then a inline fused wire to the lights and ground the relay. So basically you can only run the lights when the key is 'on' and the swtich is flipped, I do this so I will not forget and leave the lights on a drain my battery (unless I leave the key in the truck and in the 'on' position and the swtich flipped....lol). Just some thoughts.

[bd]

...I like the idea of going through the firewall to the terminal block on the firewall.  My thought was to jumper from the factory terminal block to a new terminal block and then through the firewall to the fuse block.  I plan to mount some driving lights \ work lights on the rear of the truck so I thought adding a new terminal block and using it for all of my connections might be a good idea.  I had not thought about using a fusible link between the two terminal blocks.  I like that idea.  Would a fusible link or an inline circuit breaker be better?

If I am following along correctly, the reason for coming directly off the battery to a new terminal block is to protect the lead from the battery to the factory terminal block on the firewall.  Since I plan to add at least a couple more electrical load items do you think it best to just take this approach now so it's ready when I add items later?

I believe the circuit breakers for the seats are 30 amp but I will need to double check.  The work lights will be 55 watts so that should be 10 amps for both of them.  I would expect to see a max of 40 amps in the terminal block if both lights are on and one of the seats is moved at the same time....

Mount a junction block on the radiator support or the firewall where it is most convenient for you to access without accidentally grounding it.  Choose a junction block that has a 1/4" minimum to 3/8" stud diameter, that can tolerate high current load.  Connect the junction block directly to the battery using 6-gauge cable protected by a 6-inch long, 10-gauge fusible link installed at the battery end of the lead.  Be sure to crimp and solder all terminal connections.  You can then add accessory load circuits as you please to the junction block and remotely control the loads with relays.  This method prevents overloading the factory wiring harness and its limited built-in protection.  Protect each newly added accessory with a its own individually dedicated fuse or link directly off the junction block.  By using engine compartment mounted relays to control the higher load accessories, the switches inside the cab that control the relays with low current can tap ignition, accessory, or battery power directly from the factory fuse box without worry of overload - very convenient.

For the 30-amp seat circuit, string a 10-gauge power lead protected by a 14-gauge fusible link to the seat fuse box through a bulkhead feed-through stud, as previously mentioned.  That way you will also have an additional high current battery tap inside the cab if you need it - also convenient.  You can protect the feed-through stud on both sides of the firewall using cable end insulators (pictured).

Edit:
For high current protection, you can use fusible wire, fuses, or circuit breakers.  Each has its pros and cons.  Fusible wire is more forgiving of current surges and is relatively low cost, but acts as a bottleneck to high current flow because of it's smaller gauge; and it doesn't 'fuse' at a precisely predictable overload.  Fuses are inexpensive, but also very sensitive to momentary overcurrent and fast-acting.  High-current, switchable breakers are reliable and fast acting, but not as sensitive to overcurrent as fuses; they are also fairly expensive...
http://www.delcity.net/store/Hi-Amp-Surface-Mount-!-Manual-Reset-(Switchable)/p_193073

Since the seat wiring is locally protected by breakers/fuses, use a fusible link as master protection of the wiring at the power source.

[Tx_Phil]

With the seat to me it sounds like you would be better off starting from stratch. I would run an inline fuse wire off a constant power source and you can use a distrubution block or just run a 60amp inline fuse and thicker wire to run both and power the seat from that and get rid of that whole seperate fuse block. Just also make sure that the seats are ground to a good ground. Rusty grounds are not very reliable. Unless I am not understanding right and that little black box with the fuses is what is built into the seat to make it going in all the different positions??

With work lights what I do is use a 30amp relay (pre set of lights) and a fusible link. Because work/off-road light ussually need a good power source, the best thing to do is run a wire straight from battery to realy, and then run a keyed power wire (and I brake that with a swtich) to relay and then a inline fused wire to the lights and ground the relay. So basically you can only run the lights when the key is 'on' and the swtich is flipped, I do this so I will not forget and leave the lights on a drain my battery (unless I leave the key in the truck and in the 'on' position and the swtich flipped....lol). Just some thoughts.

That little black box is a mystery relay 30A Bosch relay. Just like everything else in this fuse block is has no power either. It has light blue wire with an inline barrel fuse but nothing after the fuse barrel.  It looks like another something that was ripped out sometime in the past.

I like the idea of "belt and suspenders" for the work lights. I can see myself working late into the night and leaving the lights on all night. Dead batteries are no fun when you're over an hour away from the closest town!

[blazing816]

Yeah I did basically what 'bd' just went into full detail with my off road lights (can upload picture when get home from work) I mounted the plastic relay to the core support right by the battery. And like he said its best to have the fuse the closest to the battery side. And if for some extreme case you do overload the 30amp circuit (again do one for front and another for the back) if it heats or melts (highly unlikely) that way it is outside and will not hurt your interior any.

And as for the seat it sounds really messed up to me. With alot of wires clip, burnt out breaker...I would guess that it was previously hooked up was way wrong and thats why some one clip it. I would throw out the whole mess you pictuced (relay fuses whatever else) and start over. Your best bet would be to un-bolt the seat (if havent already) and see if there is a power board up in the seat (by where the buttons are on the seat) so you only need to run power and ground (useally when buttons are mounted right on the seat) if the power seat buttons are in door or cetner console....then you have to run a wire for each directions. If you still do not understand/cannot figure it out, it would be helpful to see a picture up the bottom of the seat...and at the back side of the controls.

My previous job was hooking up all sorts of aftermarket equipment in vechiles (mostly radios, speakers, door popers, alarms, etc.) but we did alot of power seat conversion, heat seats, and what not. But whenever going from a manual to a power seat we always may sure the seat buttons were on the seat so we would only have to run a power and ground (only of course if the customer paid enough we would put the buttons in the doors or what not ).

[Tx_Phil]

...I like the idea of going through the firewall to the terminal block on the firewall.  My thought was to jumper from the factory terminal block to a new terminal block and then through the firewall to the fuse block.  I plan to mount some driving lights \ work lights on the rear of the truck so I thought adding a new terminal block and using it for all of my connections might be a good idea.  I had not thought about using a fusible link between the two terminal blocks.  I like that idea.  Would a fusible link or an inline circuit breaker be better?

If I am following along correctly, the reason for coming directly off the battery to a new terminal block is to protect the lead from the battery to the factory terminal block on the firewall.  Since I plan to add at least a couple more electrical load items do you think it best to just take this approach now so it's ready when I add items later?

I believe the circuit breakers for the seats are 30 amp but I will need to double check.  The work lights will be 55 watts so that should be 10 amps for both of them.  I would expect to see a max of 40 amps in the terminal block if both lights are on and one of the seats is moved at the same time....

Mount a junction block on the radiator support or the firewall where it is most convenient for you to access without accidentally grounding it.  Choose a junction block that has a 1/4" minimum to 3/8" stud diameter, that can tolerate high current load.  Connect the junction block directly to the battery using 6-gauge cable protected by a 6-inch long, 10-gauge fusible link installed at the battery end of the lead.  Be sure to crimp and solder all terminal connections.  You can then add accessory load circuits as you please to the junction block and remotely control the loads with relays.  This method prevents overloading the factory wiring harness and its limited built-in protection.  Protect each newly added accessory with a its own individually dedicated fuse or link directly off the junction block.  By using engine compartment mounted relays to control the higher load accessories, the switches inside the cab that control the relays with low current can tap ignition, accessory, or battery power directly from the factory fuse box without worry of overload - very convenient.

For the 30-amp seat circuit, string a 10-gauge power lead protected by a 14-gauge fusible link to the seat fuse box through a bulkhead feed-through stud, as previously mentioned.  That way you will also have an additional high current battery tap inside the cab if you need it - also convenient.  You can protect the feed-through stud on both sides of the firewall using cable end insulators (pictured).

Edit:
For high current protection, you can use fusible wire, fuses, or circuit breakers.  Each has its pros and cons.  Fusible wire is more forgiving of current surges and is relatively low cost, but acts as a bottleneck to high current flow because of it's smaller gauge; and it doesn't 'fuse' at a precisely predictable overload.  Fuses are inexpensive, but also very sensitive to momentary overcurrent and fast-acting.  High-current, switchable breakers are reliable and fast acting, but not as sensitive to overcurrent as fuses; they are also fairly expensive...
http://www.delcity.net/store/Hi-Amp-Surface-Mount-!-Manual-Reset-(Switchable)/p_193073

Since the seat wiring is locally protected by breakers/fuses, use a fusible link as master protection of the wiring at the power source.

Well a trip to the parts store is clearly in order. Terminal block, lots of wire bits, crimp connectors, new roll of solder.
On those fusible links, is it best to just buy them pre made or is this something you typically build yourself just using lighter gauge wire?

It makes sense to not add load to the factory wiring and I like the idea of keeping all of this "non-stock" stuff on it's own.

[Tx_Phil]

BD, Blazin - I really appreciate the help guys and especially the quick responses.

I bought this suburban to use as a hunting \ ranch truck so I didn't care about the dash being 1/2 torn apart and the electric windows and seats not working and such.  Its mechanically sound so I figured I would fix just what was needed and haul it to the deer lease out in west Texas.  Last Friday at around noon my son got in a pretty bad accident and it looks like his (my) old truck will be totaled.  The good news is that no one was hurt but we are short one vehicle. He's 22 and just graduated college and working part time at Bass Pro. He's living at home and saving his money while trying to find a full time job but even having a dual degree isn't getting him anywhere in this economy. 

I figure with the suburban just sitting at my brothers house 2 hours away it would be smarter to make it road worthy than to rush out and buy something cheap.  I need to fix the horn, the AC\Heat duct work and the seats of course but that is all that left to make it road worthy. It's not pretty and it still needs stuff like drip rails and weather stripping but it will be good enough to get to work and back at least in the short term.

Again... thanks for all the help.

[bd]

...On those fusible links, is it best to just buy them pre made or is this something you typically build yourself just using lighter gauge wire?

Fusible wire is specially made for its purpose - it IS NOT regular wire.  You can purchase it in bulk lengths (some places sell it by the foot), or you can buy them pre-made in 6" lengths by gauge size with the ring terminals already installed, ready to splice onto the end of your wire.  Click here if you want to build your own...
http://forum.73-87chevytrucks.com/smforum/index.php/topic,11972.msg45217.html#msg45217

Sorry to hear about your son - good luck on getting your truck back on the road.  You're always welcome to any help we can offer.

[Tx_Phil]

Been meaning to post an update.....

I had no idea a 2 lug terminal block was so had to find. I checked every auto parts shop in 2 towns and no one had anything even close to the pictures in the post above. Granted these are small towns, under 50k population but I think I hit 12 shops or so  I even checked a couple of tractor supply places and the Chevy dealer, no dice. The Chevy house did offer to order me one but that would take over a week.

I ended up pulling an alternate to get me by. From the battery I ran a 12 gauge jumper with an inline fuse from the battery to a 12 gauge wire run through the firewall to a small terminal block. The terminal block has 4 sets of connections each insulated from each other. I terminated the 12 gauge wire with a crimp on fork type connector. I then built a small jumper to the next set of terminals. On the other side of the terminals I used the same type of forked crimp connector to connect the lead to the seats. The seats are grounded to the floorboard right under the seat. I removed, cleaned and reattached the grounds. Now I have a fully functional pair of 8 way power seats!!

One if these days I will remember to take pictures while working. Here's a short video from after everything was up and working.


And here she is behind the mechanic's shop waiting for state inspection which she passed with no issues.