ElectronicsNeed help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?
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i hate to keep coming on here with problems and not giving anything in return, but ive searched and searched trying to find a solution to my tachometer problem, so dont say i havent tried the search, ive looked through quite a few threads, im thinking its something at the coil or a bad ground, because ive bought 2 tachs, both from v8 cars from upullit, and they both do the same thing as my original, so i doubt its a resistor or a bad capacitor, it either stays pegged at zero when running or slowly rises until it pegs at 7000 rpms, this is at idle or driving, doesnt matter, and when i turn on my right blinker the tach starts bouncing all over, i also tested with my voltmeter, running on ac settings from the coil wire in the dash to ground, and i get jumpy readings
does anyone have a complete wiring diagram for the tach?
thanks
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hate to bump, but this is the last thing besides the oil pressure gauge that i need fixed, and it would be nice to have all my interior working like it should
sounds like either a short in the wiring for the cluster, or the flexible plastic circuit board on the back of the cluster. here are the wiring diagrams for the tach and the cluster circuit board.
the tach has been messed up since i bought the car, i have no idea what has been done to the engine before i bought it, all i know is it was converted to carb by the previous owner
i ran a wire directly from the coil to the tach itself, i didnt run a wire to the gauge cluster, i ran it around the cluster to the coil lead on the tach, and i got different results, but all 3 of my tachs still do the same thing, except this time they stay at about 5000 rpm, none of them peg out, i know i still have a short somewhere in the cluster or somewhere because my blinkers are kind of screwy, but what does this say about my coil? can that even go bad and the engine still run?
Mine's the same, stuck on 7000 and doesn't move. Everyone who gets in the car is like, OMG we're going seventy?? and I'm like nooo... just 65. The speedometer is over here.
Hmm curious pegs at 7000 rpm. Is the distributor HEI or does the distributor have the coil on the side? Easy way to check is there a wire in the middle of the cap or is there no wire in the middle just a big bulge. Reason being that there might be a difference in the reference signal for the tach in the 2 different dists. I will look at the wiring diagrams and see if I can help you. Have you checked both harnesses leading to the gauge cluster for rips tears in the conduit, broken wiring in the conduit, or fried wires? I will look at the diagrams I have and see if there is a solution to your problem.
__________________ -If it don't fit...force it...until it does- -My girl used to purr...Now she growls-
Last edited by z28 TPI; 11-04-2009 at 03:04 PM.
Reason: have is spelled with a v not b
the distributor just has a bulge on top, no wire, wires come out of the side of it, i had another distributor that came out of another camaro, although i dont know the year or anything of the other car, the distributor was for an 8 cyl, and it looked the same as mine, and it had a pin on the side that said "tach" or "coil" something like that, so i looked at that wiring diagram above, and wired a wire from where it said tach or whatever on the distributor, and then directly to pin 11 on the gauge cluster, and the tach just pegged at either 0 or 7000..
thats as far as i got, and i gave up on that for the time being
Last edited by wwwyzzerdd; 11-05-2009 at 01:03 PM.
Nina you are right on the open ground. Wwwyzzerdd i would really look at the wiring harness in the back of the cluster. when you turn the signals on somewhere in the harness those light are grounding out on the tach signal wire thats why it moves. After that I would check the continuity of the tach signal wire coming off the dist. it should be white in color and run to the drivers side firewall. I fthe wire color switches it would be at the connection in the firewall, but in my experience GM doesn't do that. Anyways follow that wire to the gauge cluster which means when you get to follow the wire inside the car i woulds start taking the conduit apart and follow to wire. Hope this give you a start to fixing your tach.
__________________ -If it don't fit...force it...until it does- -My girl used to purr...Now she growls-
ok i was checking wires again, there is no wire going to the tach terminal on the distributor, and the only wire hooked up to the distributor(besides the 3 already on the distributor) was pink in color and is connected to the batt terminal on the distributor, and i cant seem to find one in the harness anywhere, im going to take out the cluster again and check the wiring under the dash to see if one is even goin to the tach
i took a picture, dont know if it will help much, theres a white wire on the passenger side of the harness that doesnt appear to attach to anything, i doubt thats in, but i figured id point it out, yall might know what it goes to
Can you get a better pic of the connector? Is the wire white? It might be the tach signal wire. If it is the tach wire it will have the same style connector as the bat wire. It does look like it but I could be wrong.
__________________ -If it don't fit...force it...until it does- -My girl used to purr...Now she growls-
yeah sure, the wire is white, but its very dirty, and the connector is broken partly, the reason i didnt think it was the tach wire though is because its not long enough to reach, but hell someone couldve rerouted it for some strange reason, lot of rigged stuff in this car, lol
the batt wire has a different style connector though, but i can tell the connector to the batt is not original, someone put that there before i got it
thats it right there. Mine is also white that goes to tac. the only way to find out is try and hook it up. Maybe the wire is pinched if they removed the transmission. so it not giving you the full length. If its not the tac it wont' let you plug it in. but when i forgot to plug my tac in it did the same thing. Just plug it in and try.
kool, yeah that was it, i tested it by connecting a AA battery to the wire under the hood and testing the pin on the cluster and got a 1.2v rating, kinda low but the battery was pretty much dead so im guessing thats why the reading was so low, but there is still a problem, after connecting the wire to the tach terminal, i turn the ignition on the tach will go down to 0, then when i start the car it jumps up to 7000 then down to 5500 and stays at 5500 no matter the actual engine rpm, tach may be bad, but i doubt it, however i didnt test the other 2 tachs i have ill give that a shot tomorrow, dont feel like messing with it right now
im thinking there is a short somewhere in the harness that i cant get to, because my gauge cluster looks fine, no splits in the wiring or pcb, however my gauges and blinker lights on the inside are wacky, and my blinkers do not go off on there own after making a turn, i have to switch them off by moving the switch back into the middle position
also, dont know if i pointed this out, but when i turn on the cluster lights, all my gauges bottom out, gas, batt, temp, and tach
i just made a discovery, i took my voltemeter and connected it to the tach terminal on the cluster and the other to ground, and at idle i got a pretty steady reading of 6.15-6.40 volts, when reving the engine it will jump up to about 15 or so volts, so its working as it should, right? or should i be getting different voltage readings? the tach is also getting around 13 volts while the car is running from the battery terminal, so if thats all correct, then my problem is my tachometer right?
i did test my other tachs today, and they do sort of the same thing, except one stays at 0 or way above 7000 on top of the oil pressure needle(peg is broken off), and the other just doesnt really do anything but stick at 0, but on all 3 my oil pressure is at 15, i dont think i even have a sender hooked up to the oil guage, so why is it reading that? probably a short i know, theres a short somewhere thats obvious, so im gonna stop complaining about that, lol
thanks a lot for all the help, much appreciated
Last edited by wwwyzzerdd; 11-10-2009 at 03:37 PM.
Whoops. It obviously was another poster. Someone told me wrong about the PM. They shall be forced to cross the track at the start of the next Homestead 400.
If People Drove Any Slower They’d Be Going Backwards
Fog lights are not driving lights. They look doofy. Turn em off slow pokes.
How bout those nervous nellies too scared to drive without headlights on in the daytime or if there is a little rain!
. .
[/quote]
I can NOT let this quote fly.....
Fog lights... GM Service parts Catalog refers to our fog lights as "driving lamp assembly"... they ARE driving lamps.
driving with lights on in the day... ever heard of DRL's? (daytime running lamps) all canadian built GM's came with them, EVEN canadian thirdgens.
and as for lights on in the rain? in many cars, including my cadillac, after a certain period of time with the wipers on (20 seconds in my caddy) the BCM automatically activates your head lamps. and in SOME are's there are local laws and state laws dictating thet your head lamps must be on in the rain. GET YOUR FACTS RIGHT!!!
for the guys who were following this thread to fix there tachs, turned out just to be the resistor that so commonly failed on the 90-92 cars, so no matter if its a 90-92 car or not, its worth checking out
after im done messing with this tach, all thats left is the gas gauge, cause even though i thought it was working, i ran out of gas today thinking i had half a tank
anyways thanks for all the help
Last edited by wwwyzzerdd; 11-16-2009 at 06:23 PM.
, im thinking its something at the coil or a bad ground, because ive bought 2 tachs, both from v8 cars from upullit, and they both do the same thing as my original, so i doubt its a resistor or a bad capacitor, it either stays pegged at zero when running or slowly rises until it pegs at 7000 rpms, this is at idle or driving, doesnt matter, and when i turn on my right blinker the tach starts bouncing all over, i also tested with my voltmeter, running on ac settings from the coil wire in the dash to ground, and i get jumpy readings
If People Drove Any Slower They’d Be Going Backwards
