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  • March 28, 2024, 05:49:36 AM

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Author Topic: Ok, here is a weird one....  (Read 4965 times)

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Offline Amc1320

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Ok, here is a weird one....
« on: February 22, 2013, 10:44:58 PM »
A little background for the experts

Rebuilt engine
All the vacuum hoses removed, exept for PVC, 4wd and vac advance
hei one wire dist

So, hooking my tach bask up, connected the wire from the tach place on the dist to the green wire on the harness

Tach works, sorta, BUT

Only when turn signals are blinking, each time the signals flash it jumps to the correct rpms then back to zero

Also I have power windows, so if you roll up the window but continue to press the switch after the window is all the way up the tach works great perfect, until you stop trying to "over" roll up the window!

What the......

Everything else electrical works fine

So if i want to know my rpms I just have to turn?

Thanks
Rob
Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

Offline eaglebeek

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Re: Ok, here is a weird one....
« Reply #1 on: February 22, 2013, 10:51:16 PM »
Check for ground for your tach... :eagle:
1984 Eagle Wagon, 258, auto, 2.73 gears, daily driver
1983 Eagle Limited Wagon, parts; sold
2000 Jeep Cherokee, 4.0, auto
2007 Hyundai Accent, radical downsize from minivan, wife's car and she loves it!

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Offline ammachine390

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Re: Ok, here is a weird one....
« Reply #2 on: February 22, 2013, 11:09:52 PM »
Is this a stock tach or an aftermarket? Stock tachs ground through the negative post of the ignition coil. If it's aftermarket and has a separate ground wire and the trigger wire to the negative of the ignition coil, then I agree with eaglebeek, check the grounds.
Dan
1981 AMC Concord DL 258 Auto

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Offline Amc1320

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Re: Ok, here is a weird one....
« Reply #3 on: February 22, 2013, 11:13:50 PM »
It's the stock tach, I agree it's a ground somewhere, i don't think it's in the dash must be under the hood somewhere, after all it was all removed and replaced, musta missed one somewhere

It's just weird that's it related to the turn signals

Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

Offline vangremlin

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Re: Ok, here is a weird one....
« Reply #4 on: February 23, 2013, 08:05:28 AM »
The stock tach grounds through the upper left mounting screw where it attaches to the instrument cluster, and it looks like it shares a common ground with the turn signals and various other lights on the cluster.  Here is a picture of the back of the cluster, the ribbon on the printed circuit board goes to about the 9:00 position on the round connector.  Please don't mind the slippers  :rotfl:

PS that box in the background is your hood trim waiting to be shipped today Amc1320.

1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline rollguy

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Re: Ok, here is a weird one....
« Reply #5 on: February 23, 2013, 11:25:24 AM »
Cool slippers! (disregard that, you said not to mind the slippers).
1980 Eagle Turbodiesel Wagon (only 2 known to exist as of 2008)- 7-7-2011 Flight to it's new nest @ Rambler Ranch
1983 Eagle Wagon  Tan over Copper
1982 Eagle SX4 "ALTREGL"  (avatar photo)
1982 Eagle 4 Door Sedan  Copper over Satin Black
1985 Eagle Sport Wagon October 2007 ROTM (SOLD)
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Offline eagleman

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Re: Ok, here is a weird one....
« Reply #6 on: February 23, 2013, 11:44:03 AM »
Wish I had a pair of blue slippers like those! You said pay no attention to the slippers but I just had to respond there so  well you know, cool. yeah thats it cool.lol
Turkeys walk.Eagles fly!!!

Offline vangremlin

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Re: Ok, here is a weird one....
« Reply #7 on: February 23, 2013, 02:16:54 PM »
Thanks, and those slippers rock by the way.  I don't think they make that particular style anymore thoush, so I'm trying to keep them going....kind of like our Eagles.
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline Amc1320

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Re: Ok, here is a weird one....
« Reply #8 on: February 23, 2013, 04:55:59 PM »
Ok, heres some further investigation

THe tach works fine with the headlights OFF, does not work when the lights are on??

huh?
Rob c
84 Eagle Limited Wagon (driven everyday)
81 Eagle Kammback
81 Spirit (undergoing surgery)
83 Spirit (parts car giving it all to keep the rest going)
Manchester, TN

Offline carnuck

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Re: Ok, here is a weird one....
« Reply #9 on: February 23, 2013, 05:12:10 PM »
Try jumper cables from the battery negative to something clean metal (possibly bumper face) with the lights on and see if it works. That would be missing/broken/corroded body to battery negative strap. Headlights will also get brighter and battery will get fuller.
AMC/Jeep gauges are for amusement only. Any correlation between them and reality is purely coincidental!

Offline framedoctor

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Re: Ok, here is a weird one....
« Reply #10 on: May 26, 2023, 09:04:44 PM »
Ground issue. Good luck. My gauges top out if i turn headlights on. I cant find issue. several tried to help me but understanding electrical is not my skill.

Offline Trooper

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Re: Ok, here is a weird one....
« Reply #11 on: May 27, 2023, 05:48:00 AM »
There is a ground point on the firewall in the engine bay between the back of the engine and the brake booster. There may be one or several wires grounded there. Make sure it is a good ground.

Offline mo.eagles

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Re: Ok, here is a weird one....
« Reply #12 on: May 27, 2023, 12:06:10 PM »
A friend of mine had a Gran Torino that had an engine rebuild. When you opened the door the starter would start cranking. Found ground strap to body was cut. Electricity will do funny things.
'85 wagon Limited   tilt wheel , cruise control
power seats ,windows and locks
rear window washer /wiper 
tach and gauge package
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 '85 wagon   power windows and locks
rear window washer/wiper
factory tow package
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Offline EagleSX4_5Speed

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Re: Ok, here is a weird one....
« Reply #13 on: May 28, 2023, 08:11:52 AM »
You need to put a resistor in line with the tach wire. My dad also put a HEI distributor in and had the same issues with the tach until he added an inline resistor. He had to try a few before he found one that worked.
« Last Edit: May 28, 2023, 08:13:19 AM by EagleSX4_5Speed »

Offline framedoctor

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Re: Ok, here is a weird one....
« Reply #14 on: July 17, 2023, 09:16:36 PM »
My gauge issues were solved, bad ground on firewall. Blinker and or headlights would max out my gauges.

 

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