Ok folks here we go. I've Been merging my 77 gmc with my 87 and I've run into a interesting situation, my dash ,From the 87, doesn't have power to any gauges. I used the engine side harness from my 77 and plugged it into the 87 harness in side. it starts and runs turn signals and head lamps work along with instrument panel lighting. But no gauges I'm temped to go back to the 77 interior harness and gauges but one trace is broken on the 77 cluster. Another reason, to use the 87 cluster, is the cruise control speed censer is in the speedo head, and will not fit in the 77 housing. I've traced the problem to the pink with black wire at the cluster, no voltage, which goes to the fuse panel all the fuses are good. If i jumper the wire my oil pressure gauge wants to spin. but my voltage gauge works and still no working fuel gauge it rests at 1/4 tank. I do have power to the pink cluster wire. the diagram i have been working with doesn't show how power gets to this point in the fuse box tenth wire down on the left side the other reasons I want to use the 87 harness are the rear window power, power window power and rear air power. I may have to abandon the 87 harness and adapt the 77 harness but if anyone has any suggestions I would be great full. I'm work with very little money but alot of heart. I can adapted the 87 steering column to the 77 harness if needed but to tell you the truth I feel like it's got to be some thing stupid I'm just not seeing. HELP
Why are diagrams so vague in some ways? not for me to know I guess. . Well went back to the 77 GMC harness and decided on relays for all my addons. I had to go back to an old saying ' if it ant broke don't fix it'. I will post my success' on my '77 GMC panel' pics as they develop wish me luck!
yeah um i say screw that this is why i want like a old 66 chevy or somthing, nice and siple and smog excempt
Dashboard Fun I'm surprised I didn't see this before . I'm in the same boat with my '76 GMC ~ as it turns out , GM changed the placement of various wires in the MPC connected to the back of the dash insert , this makes it fairly simple to adapt a newer dash binnacle to an older truck or vice-versa . Just take some time and test what goes were , not trusting the generic wiring diagram , use it as a general guide instead . When I'm done , my old base model Jimmy will have factory clock and gauges from a newer Suburban instead of cheapo idiot lights and it'll be nice & bright as i'm hand cleaning & polishing every single part whilst I have it all into it's basic parts . How did this work out for you in the end ? . any pix ? .
Update I decided to use the short version of the serenity prayer( Fu**it). and I have abandon the majority of the 87 harness,I was able to make the rear window work and able to get power to the rear air system. now I need to make or get a pig tail's for the 87 wiper motor, so I can use the steering column turn signal wiper controls. For some reason as far as I can tell there are 4 different types of motors, between 76 and 88 using various types of switches. I have three gm model trucks a 77 a 80 and a 88. The 88 is on the turn with delay, so of course its different. a friend gave me a dash switch from a 78 all three are different, 77, 78, 80. They look similar on the face but all three have different plugs, I also have three wiper motors 77, 80 and 87, they all bolt up the same but operate differently from one another electrically. fun fun fun. I guess this is called automotive engineering job security.
Oh, V W nate. I had a 75 Jimmy and I was able to use the tach and the fuel gauge from a 77 RS Camaro . I put the fuel gauge from the Camaro where the clock was and with minor modifying then put the tach where the fuel gauge was. It looked great like it was stock. until some kid rear end me doing 55mph while I was stopped. dam I loved that Jimmy. I miss my back and neck too.
Dash Board Fun A tach really would change it from woes to ! WOWS ! . As I have a <magic> Hot Rod muffler , I don't need a tachometer , I can hear the engine just fine . I forget what brand it is but my son says it's really good and expen$ive , I think it rather too short even if it is a flow through design as longer mufflers make for deeper exhaust note ... you can tell I'm an old fart , right ? I'd best love to have a 46" long Smitty's on it but I digress . I used your nice colored diagram to work my dash up to a 'T' ~ everything works now and I love it , I dunno why GM changed the pin connections in the MPC so many times but knowing , made it relatively easy , I just starteed with piles 'o parts , A test light , pad & paper , I made some photocopies of the floppy PC sheet and had at it . I too have a wonky wiper motor , the early wiper switches have different mounting too , I guess so you don't goof by installing the wrong wiper switch but I'd sure like that delay wiper I saw in an '85.... I've put over $2,500 in parts into this poor old $700 work truck , I hope I can sell it someday when I get finished with it .
The Back Thing OBTW : I'm sorry you're suffering this too , loosing an L1 vertibrae sux BIG TIME but I'm lucky to be alive much less walking , albiet with a cane and a back brace . I even bought a new Moto and will go find out if I can still ride when it's ready for pickup Don't ever give up ! . soldier on my son .
Ok wiper motor? What yr. Is the motor a plain motor & pump? Or does the motor have no pump plain. Or does it have motor & pulse with pump. Or Motor only with pulse. Pics of the stock switch & motor? You’re working with. What option of dash or wiring are you trying use or clone.
Wiper Fun It's a '76 BUT , it has spent many a year driving in Mexico so God along knows what was grabbed and slapped onto it as it was broken here & there . It's the basic GM wiper & WSW pump from the 70's , I remember them well from my dealer days .
to answer the Question my wiper motor 'in the 77' is stock the one I plan on installing is out of a 87 GMC Suburban. Time has been been very tight lately Wife had surgery both boy's Have been sick including myself and had to get an attorney for Voc. rehab. experience. new project now is installing Sentinel head lamp system from my 91 caprice it looks fairly cut and dry I found some Mitchel Diagrams which look pretty good for this project. they are as fallows. for the 91 caprice for the 77 gmc I can only see two wires that are different. I'm going to make up a bench bench test system for this before I try to install the system, wish me luck. I start to night.
Bench test went well now to decided which switch? the 91 Caprice or the stock pull out type? I will try and mock up a dash set up and send Pics.
Wiper Switch ?? Can't you use the stock slide typ wiper switch with the intermittent feature ? . That's what I'll up grade to if I ever fiddle with the wipers again .
I'm assuming That with the 76 type motor, I Know there is a Pulse system for the 77 slide type. although I don't know if the 76 motor will work with it. but I did find a 'ski' for the 87 wiper 'pulse control system' with each component ( transistors cap's resistors etc.) So I'm going to build one. and see what happens., or find a bad unit and rebuild one. I have the 87 wiper motor for this. I've also found some timer circuits using a 555 timer IC. If There' a way to make it work I'll find it.
Ah , SO ! NOW I understand . A very good idea , that . Keep up the good work and keep us posted please .
