B-Man Posted March 24, 2023 Share Posted March 24, 2023 Starting a thread on some planned and unplanned wiring on my 72 as I get going working on it. I just ordered this 18 x 24 wiring diagram for $36, including shipping. I love working from these really nicely laid out and colored diagrams. It's an artform!! I bought one for a 78 Triumph Spitfire that I picked up a few years ago and it's SOOOOOO valuable to have! https://classiccarwiring.com/products/1972-chevy-chevelle-malibu-monte-carlo-color-wiring-diagram?variant=40725685207240 First challenge: The nose casting on my starter cracked the other day, partially stripping some teeth off the flywheel (ugh!). I dropped the starter and quickly discovered that a number of folks with good intentions have had their hands in the wiring over the years (ugh!). As I started peeling back the onion I've realized that the can of wiring worms is growing bigger and bigger. So ... first wiring challenge will be correcting all of the ignition wiring to the starter which inexplicably has worked fairly well for the year that I've had the car. More later! Quote Link to comment Share on other sites More sharing options...
DragCat Posted March 24, 2023 Share Posted March 24, 2023 Let us know how you like the wiring diagram. Even tho the PO and myself have modified some stuff might be good to have as a reference . On my blue oval I found a company that copied the factory tech manual pages (12)I had Kinko's (yea I'm old) blow them up to architectural size so I could read them without my glasses 🤣I'd still like to play whack a mole with the group that designed that nonsense 🤣 I didn't care for their diagrams on the Monte Quote Link to comment Share on other sites More sharing options...
cbolt Posted March 24, 2023 Share Posted March 24, 2023 That is actually fairly common, the starter wiring harness being a mess, due to its location and heat. If anyone worked on the starter or that general area and were not attentive to where the wires are supposed to be routed they will at best case become brittle, at worst case melt the insulation and short out. You should be able to get it sorted fairly easily, but know that there are several sources for a new harness if it comes to it. Quote Link to comment Share on other sites More sharing options...
B-Man Posted March 25, 2023 Author Share Posted March 25, 2023 @cbolt, yeah all too common and not at all unexpected. I looked up some wiring harnesses and boy do those seem like the way to go eventually for sure!! For now I'm just going to trace and replace the obvious issues. I've got plenty of wire and wiring bits and I sort of enjoy the hunt too. It's amazing see a few large gauge wires with the jacket burned right through to the stranded wire, near the headers of course. With a bunch of oil all over the place from bas front and rear seals, it's unbelievable the car hasn't burnt to the ground already. Fun fun! I will report back with pictures once I really start digging in Quote Link to comment Share on other sites More sharing options...
B-Man Posted March 25, 2023 Author Share Posted March 25, 2023 Follow up - I just ordered this starter off Summit https://www.summitracing.com/parts/sdm-pce3931032 Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 9, 2023 Author Share Posted April 9, 2023 A reminder ... this all started due to a broken starter. And here I am redoing A BUNCH of wiring! The big, laminated wiring diagram linked above is awesome. Totally worth the $35 or whatever. I will probably end up hanging it on the wall - sort of an art piece to be honest. Above the brake booster is the Horn Relay. There are a number of 12V heavy gauge wires that come in to that point, including the direct line from the battery / starter / alternator. Almost all of these wires, at multiple points, were burned through. It's really incredible the car never burned to the ground. While a full harness replacement is probably in the future, for now I'm just pulling back all of the electrical tape and loom and checking / fixing every wire and connector. Hopefully I will get enough of the wiring repaired to get the starter back in this afternoon. We shall see! 3 Quote Link to comment Share on other sites More sharing options...
DragCat Posted April 9, 2023 Share Posted April 9, 2023 Thanks for the update on the laminated colored schematic. I will have to order one for the garage wall too. 🤣 As far as your other comments, and that's the "snowball effect" ! 🙃 But on a good side, going through the harness should lower your possibility of a critical electrical issue on the road or even worse fire. 2 Quote Link to comment Share on other sites More sharing options...
Rob Peters Posted April 9, 2023 Share Posted April 9, 2023 That reminds me, We need to buy some spaghetti when we go to the grocery store tomorrow. rob 4 Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 12, 2023 Author Share Posted April 12, 2023 I got the new mini high torque starter installed and all of the wiring squared away. It started up on the first try. Yay!! All is well ... Except ... the new alternator is not charging. Dang it!! This is just a standard alternator I picked up at OReillys since the old one is so gunked up and the positive post spun on me as I tried to take the nut off (unit now questionable). I have to think that it's good since it's new. But I guess one never knows. When I kick the key forward the alternator light comes on dimly lit and I'm only getting about 9vdc at the igniter wire. Should be 12vdc or whatever the battery is reading I believe. So there is some significant resistance somewhere. As I understand it, if the igniter wire doesn't get 12 volts, it doesn't kick the internal voltage regulator on. True? So I have some troubleshooting to do before I bring the alternator back. The 2 wires to the alternator are pretty stiff and old. I should have reran new ones before I loomed everything. I will unloom it all and trace those wires back, next step. 1 Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 13, 2023 Author Share Posted April 13, 2023 Update on the alternator - I ended up pulling the brand new alternator out, bringing it back to OReillys for a bench-test, and determined that it was a faulty unit right out of the box. In all my years I've never had that happen on starters, alternators, etc I dont think. But there it is! I will be picking up the new alternator, as well as a new voltage regulator from the parts-cannon, this afternoon. And I have a new 2-pin connector coming from a vendor on Amazon as well. So fingers crossed my minor alternator saga will be figured out. Note that the old alternator was charging just fine. But when I took the nut off of the + post on the back of it the post started to turn - someone had used a lock-nut on that post ... ugh!!!! I suppose I could have opened up the alternator and tried to fix the post, but there was so many years of built up crud on it and in it that it didnt seem worth the time. Worst case scenario though, I could try a DIY rebuild and put it back on - no plan to do so though. I'm hoping this ends this thread for now and I can continue driving my MC for the summer. I suppose I should tackle the dash lights not coming on too ... hmmm. We shall see 1 Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 15, 2023 Author Share Posted April 15, 2023 Update: ALTERNATOR IS STILL NOT CHARGING!!!!!! Man, what a pain in the butt. - I threw in the new (replacement) alternator and new voltage regulator. - I connected in the new 2-pin connector and plugged it into the alternator - I pulled the starter back out, fixed the melted wire loom (forgot to tie it back from the header), confirmed the 10 gauge wire back to the alternator is intact, and reinstalled the starter - I now get 11.6v to Pin 1 (exciter wire) on the 2-pin alternator connector vs 9v previously - With the key forward the Gen light is now much brighter ((11.6v vs 9v likely) - The Gen light on the dash does not go off when I start the engine, indicating it's not charging - The battery is down to just over 12v whether the engine is running or not. Could I have killed another brand new alternator somehow? And how would I have killed the first alternator? I'm definitely not understanding something Quote Link to comment Share on other sites More sharing options...
Scott S. Posted April 15, 2023 Share Posted April 15, 2023 It may be a bad regulator ? Or maybe the battery itself ? With the engine running and charging, the battery should be getting 13.2-14 volts..... So to me it seems like the regulator is restricting the charge. How long does the battery hold the 12 volt charge when it isn't running ? Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 15, 2023 Author Share Posted April 15, 2023 7 minutes ago, Scott S. said: It may be a bad regulator ? Or maybe the battery itself ? With the engine running and charging, the battery should be getting 13.2-14 volts..... So to me it seems like the regulator is restricting the charge. How long does the battery hold the 12 volt charge when it isn't running ? @Scott S., the battery is nearly brand new. I replaced it a few months ago and have barely put any miles on the car. The voltage regulator is brand new, and I confirmed continuity from its terminals back to the alternator 2-pin connector. Yeah agreed, something is preventing the alternator from charging. The regulator is definitely signaling to the alternator to start charging. It just isn't. The battery will of course hold a charge until it doesn't. The voltage will eventually creep down and then not allow the HEI to operate, or the starter for that matter Quote Link to comment Share on other sites More sharing options...
DragCat Posted April 15, 2023 Share Posted April 15, 2023 1 hour ago, B-Man said: Could I have killed another brand new alternator somehow? And how would I have killed the first alternator? I'm definitely not understanding something I'd go get it bench tested, eliminate or confirm there is an issue . Hard to trouble shoot not knowing what's actually good. Just my .02 1 Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 15, 2023 Author Share Posted April 15, 2023 31 minutes ago, DragCat said: I'd go get it bench tested, eliminate or confirm there is an issue . Hard to trouble shoot not knowing what's actually good. Just my .02 Yeah, I'm going to be pretty embarrassed if I burnt up a 2nd new alternator. The current new alternator I had bench tested when I picked it up and it checked good. Whereas the 1st one tested bad. But yeah, a bench test will prove or disprove. Dang it!! 1 Quote Link to comment Share on other sites More sharing options...
Dtret Posted April 15, 2023 Share Posted April 15, 2023 Just now, B-Man said: Yeah, I'm going to be pretty embarrassed if I burnt up a 2nd new alternator. The current new alternator I had bench tested when I picked it up and it checked good. Whereas the 1st one tested bad. But yeah, a bench test will prove or disprove. Dang it!! It’s very possible you didn’t burn it up. Reman quality is not that great. And so what if you did make them replace it anyway, they wouldn’t know you did it. 1 Quote Link to comment Share on other sites More sharing options...
DragCat Posted April 15, 2023 Share Posted April 15, 2023 31 minutes ago, B-Man said: Yeah, I'm going to be pretty embarrassed if I burnt up a 2nd new alternator. We won't say anything.........except here of course 🤣 And like Dennis said, I'm pretty sure everyone has gotten bad outta the box once or twice Quote Link to comment Share on other sites More sharing options...
B-Man Posted April 16, 2023 Author Share Posted April 16, 2023 Ah man ... classic error. I had the wires swapped on the 2-pin connector. I would have bet a paycheck that the 1 position was the F (Field) wire. I just cleaned up all of the gunk off my old alternator to reinstall it. Once all the gunk was gone I could CLEARLY see that Pin 1 is R (Reference 12V) and pin 2 is the F. Can't believe how much time I spent not believing I had it backwards!!! The new alternator doesn't have any markings on it. So it's a guess. Thank goodness I saw the markings on the old alternator and put 2 and 2 together. The wiring diagram I bought is correct. It's just that the pin numbering on the voltage regulator does not correlate with the pin numbering on the alternator. I wonder if it is supposed to (?). So, the alternator saga has now come to a close. I'm getting >14v on the battery right now when the car is running, and the GEN light goes off once it starts. All is well with the world of my 72 Monte now. Time to go enjoy driving it for a while before I take on anything major. Have fun everyone. 4 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 16, 2023 Share Posted April 16, 2023 Glad you found it! You will never do that again! Ask me how I know. Lololol congrats!! 1 Quote Link to comment Share on other sites More sharing options...
DragCat Posted April 16, 2023 Share Posted April 16, 2023 5 hours ago, B-Man said: Ah man ... classic error. I had the wires swapped on the 2-pin connector. I would have bet a paycheck that the 1 position was the F (Field) wire. Can't tell ya how many times ive asked my buddy to stop by and help me out, fixed in 2 minutes 🤣 As Tom said, youll never do it again, lesson learned 1 Quote Link to comment Share on other sites More sharing options...
DragCat Posted December 31, 2023 Share Posted December 31, 2023 On 3/24/2023 at 11:56 AM, B-Man said: I just ordered this 18 x 24 wiring diagram for $36, including shipping. I love working from these really nicely laid out and colored diagrams. It's an artform!! I bought one for a 78 Triumph Spitfire that I picked up a few years ago and it's SOOOOOO valuable to have! https://classiccarwiring.com/products/1972-chevy-chevelle-malibu-monte-carlo-color-wiring-diagram?variant=40725685207240 Just a 👍 for the product, Santa dropped one off for my imaginary 70 🤣 They didnt make one for my blue oval 🙃 but I have my 12 page factory schematic so its all good 🤘 1 Quote Link to comment Share on other sites More sharing options...
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