MC1970U Posted January 10, 2012 Share Posted January 10, 2012 Hello all, As many of you know, after whining about my bad clock repair experience, I have my dash apart. I have a couple electrical issues left unresolved. 1st. The amp gauge was not working in the car but when I pulled it out and tested the gauge it worked fine. It appears that the brown wire, see pictures, going from the negative terminal of the coil ends up connected to the amp gauge/tach? That wire travels from the coil, through a really rough hole in the firewall, taped up into the under dash wiring and ends up in the number 9 contact of the dash gauge wiring connecter. After doing a little trouble shooting with my meter I think that is what is happening. If the gauge package was factory to this car why was there such a crude firewall hole cut for that wire. Take a look at both the hole and the gasket? Do you have any ideas if this is correct and why it might work out of the car but not mounted up? Any schematics available for the amp gauge? My factory manual just shows a light. 2nd Any ideas on the resistor that is attached to the ignition wire? Thanks, spoony Quote Link to comment Share on other sites More sharing options...
MC-71 Posted January 10, 2012 Share Posted January 10, 2012 The only help I can give you is, that is not correct for your Monte. If you plan on keeping this car I would consider buying a new wire harness for you dash and engine compartment. Little costly but cheap insurance on your investment. Check www.factoryfit.com They make the best replacement harnesses. Quote Link to comment Share on other sites More sharing options...
monte70car Posted January 10, 2012 Share Posted January 10, 2012 Does your dash have a tach in it or it is the large fuel gauge? With the brown wire having the round plug on it and going to the number 9 pin location is for the tach. the Amp uses two wire which go out to the regulator there is a link to the pin location for the cluster plug. Quote Link to comment Share on other sites More sharing options...
MC1970U Posted January 10, 2012 Author Share Posted January 10, 2012 Ok ok I am a little closer. I found some great information and after reading it I understand this a little better. 9-brown coming from coil is for the tach. The ammeter is number 3-black/white and number 4 black. Still not sure what the resistor on the firewall is for and why the factory would install such a shoddy hole, looks like they used a large punch, for the tach wire? spoony Quote Link to comment Share on other sites More sharing options...
monte70car Posted January 10, 2012 Share Posted January 10, 2012 Spoony where that red wire is going out is a plug which is removed for the wiring of the 400 trans I would say someone add that red wire as I have never seen anything like that and the crimp slide on plugs tell me its an add on someone put in. I would try and trace the black wire coming off the resistor and see where it goes. As for the hole the tach wire comes out of is correct and what the factory probably did was used a drill bit for the hole as the firewall is pretty much the same on non-tach option cars and ones that got the tach. Quote Link to comment Share on other sites More sharing options...
MC1970U Posted January 10, 2012 Author Share Posted January 10, 2012 Robert, I was composing my last reply as you posted yours. This is all correct. I found this page http://hem.bredband.net/chevellegearheads/documents/Idiot%20light%20to%20gauge%20conv.pdf which had the info you linked. Great stuff. All is correct. Do you have any idea about that resistor? It looks to have been installed around the same time as the after market radio and there may have been some kind of security system at one time? Also what about that firewall hole and grommet for the tach wire? Would GM have done it that way? I will have to clean that up. Anyone have pictures of what it is supposed to look like? spoony Quote Link to comment Share on other sites More sharing options...
MC1970U Posted January 10, 2012 Author Share Posted January 10, 2012 Hey Robert thanks for your help, Spoony where that red wire is going out is a plug which is removed for the wiring of the 400 trans I am not sure I understand what you mean. Do you mean that is a factory plug meant for the 400 but someone has used it for this red wire that goes to the ignition wire. "As for the hole the tach wire comes out of is correct and what the factory probably did was used a drill bit for the hole as the firewall is pretty much the same on non-tach option cars and ones that got the tach." Like i said the engine side looks nice but the interior side has pushed out jagged edges like some one used a punch. They may have used a bit to start the hole but I think a punch finished it up. The rubber grommet you see in the picture is just hanging there as it is way to large for that hole? "I would try and trace the black wire coming off the resistor and see where it goes." I will do that in the next day or two. Got to call it a night. I will report my progress in the next day or two. Really appreciate the help. Thanks, spoony Quote Link to comment Share on other sites More sharing options...
monte70car Posted January 10, 2012 Share Posted January 10, 2012 Spoony for the gromment for the tach yes that's the way GM did it from the factory that gromment will push tightly into the hole. I though I had a picture of the firewall in that area but I cant find it.On the inside of the car there is a sound pad that goes on the firewall and covers it up. As for the resistor that is not a factory item most likely they probably used it to carry power to the alarm system or maybe to the radio. See if the resistor has power on it with the key off if it does then its probably used to break down the power for the alarm. I am not sure I understand what you mean. Do you mean that is a factory plug meant for the 400 but someone has used it for this red wire that goes to the ignition wire. yes that is a plug which can be pushed out if a 400 trans is installed. Quote Link to comment Share on other sites More sharing options...
stangeba Posted January 10, 2012 Share Posted January 10, 2012 I added the gauges (from a donor 71) to my 71 NON gauge car about 22 years ago. I ran the brown tachometer wire through the square hole that was covered by the black plastic grommet cover thing like in your picture. Three years ago I redid it, drilling a hole for the brown tachometer wire. Here are some pictures of the dash, heater core project that may help. The resister block looks to me like a repair replacement for the OEM resister wire that goes to the coil. Drilled hole for brn tach wire Pictures of dash htr core replacement and more Quote Link to comment Share on other sites More sharing options...
MC1970U Posted January 16, 2012 Author Share Posted January 16, 2012 Thanks everyone for sharing thus far. I have not worked on the Monte in a couple of days. I am real interested in where the other end of that resistor goes to! Bruce, I have used that link dash/heater core link many times. Thanks for making it available to all of us. I Will let everyone know what’s up when I get a chance. Tomorrow we go play in the snow. spoony Quote Link to comment Share on other sites More sharing options...
FASTSS454 Posted February 5, 2012 Share Posted February 5, 2012 I believe that resistor is for the coil, the oem wiring had resistance wire as part of the harness and it might have failed and was removed at some point in time. Quote Link to comment Share on other sites More sharing options...
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