Veraciousreasoning Posted September 20, 2021 Report Share Posted September 20, 2021 Hey all, I got a 1980 720 and was wondering if anyone has had a problem with their "RPM gauge". Mine works until I hit second gear and then stops. Wondering if anyone has a video that shows how to fix it or do I just go ahead and buy a new one from amazon and install it? I am also wondering if anyone changed their instrument cluster into something more modern and has any resources that I can use to see what it would look like? I dig the old look but may want to change it. Seeing how viable it is to do. 1 Quote Link to comment
datzenmike Posted September 20, 2021 Report Share Posted September 20, 2021 a/ Is this a factory tach?????? or some aftermarket thing wired in by non electrical electrician?????? b/ Are you saying the tach only works in first gear and not any of the others??? c/ The tach can't possible know when you are in 2nd gear. Unless an after market tach badly wired up, it's not wired into the transmission so you are either loosing power to the tach or loosing the tach signal from the coil. If it works in first there's no way it can shut one of them off in second. There are no substitutes for the dash though the '83 and up changed to round gauges and (I think) looks nicer. 1 Quote Link to comment
captain720 Posted September 20, 2021 Report Share Posted September 20, 2021 Wow it works only in first gear? That's one of the weirdest ones I've heard. Is it possibly a loose wiring that gets wiggled in and out when you shift? 1 Quote Link to comment
datzenmike Posted September 20, 2021 Report Share Posted September 20, 2021 Very likely anything .... if this is an after market tach. 1 Quote Link to comment
Charlie69 Posted September 21, 2021 Report Share Posted September 21, 2021 Tac signal is taken from the exhaust coil. Quote Link to comment
Veraciousreasoning Posted September 21, 2021 Author Report Share Posted September 21, 2021 On 9/20/2021 at 1:23 PM, datzenmike said: a/ Is this a factory tach?????? or some aftermarket thing wired in by non electrical electrician?????? b/ Are you saying the tach only works in first gear and not any of the others??? c/ The tach can't possible know when you are in 2nd gear. Unless an after market tach badly wired up, it's not wired into the transmission so you are either loosing power to the tach or loosing the tach signal from the coil. If it works in first there's no way it can shut one of them off in second. There are no substitutes for the dash though the '83 and up changed to round gauges and (I think) looks nicer. A. This is a factory RPM gauge b. The RPM gauge shows me my rpms in first and second but nothing after that. When I hit third gear it stays roughly 1-2rpm and even though I push the pedal to the floor it never moves. 1 Quote Link to comment
datzenmike Posted September 21, 2021 Report Share Posted September 21, 2021 What in the wide wide world of sports would cause this??? OKay 1 and second works but 3rd and 4th don't. Goes it come back when the shifter is in the neutral gate between 3rd and 4th??? What happens if you shift out of 3rd into neutral and let the clutch out? Trying to see if one of the transmission emissions switches is involved. 1 Quote Link to comment
Veraciousreasoning Posted September 21, 2021 Author Report Share Posted September 21, 2021 2 hours ago, datzenmike said: What in the wide wide world of sports would cause this??? OKay 1 and second works but 3rd and 4th don't. Goes it come back when the shifter is in the neutral gate between 3rd and 4th??? What happens if you shift out of 3rd into neutral and let the clutch out? Trying to see if one of the transmission emissions switches is involved. Yea its the strangest thing to be honest. If I get above second gear it basically just sits at 1,000-2,000 RPMs in gear and in neutral. It looks like it moves but the movement is so small that you can't even tell its above 2,000 or it could just be my shit eyes thinking it's moving. I've tried 3rd then neutral, 4th than neutral, and 5th than neutral. Nothing moves it. The second I go to first gear at a dead stop I can get the needle above 2,000-3,000 rpm (I only do that when testing it) 1 Quote Link to comment
datzenmike Posted September 22, 2021 Report Share Posted September 22, 2021 Hold on. Above 2,000-3,000??????? or working normally to 5,000? 1 Quote Link to comment
Veraciousreasoning Posted September 22, 2021 Author Report Share Posted September 22, 2021 3 hours ago, datzenmike said: Hold on. Above 2,000-3,000??????? or working normally to 5,000? Let me try to explain this a bit better as I feel like we are getting our wires crossed here. When my car is at a dead stop I can give it gas and the tachometer moves normally. When I am in first gear it moves normally. I usually shift around 3,000-4,000 RPMs Second gear moves normally. The second I get to Third gear the RPM gauge usually sits around 1,000-2,000 and doesn't move even if I floor it and give it all she got. The engine will be screaming like its at high RPM but its still not moving and if it does move it moves not even a 1/1,000 of a inch. I don't even know if it moves or it's just my eyes thinking it moved slightly. 1 Quote Link to comment
Lockleaf Posted September 22, 2021 Report Share Posted September 22, 2021 Video is probably going to be necessary on this one. Very odd. 1 Quote Link to comment
Veraciousreasoning Posted September 22, 2021 Author Report Share Posted September 22, 2021 9 hours ago, Lockleaf said: Video is probably going to be necessary on this one. Very odd. I am going to try to make a video here shortly. It is really just a strange thing I've never seen/experienced it. 1 Quote Link to comment
datzenmike Posted September 22, 2021 Report Share Posted September 22, 2021 A video will only show what you said that it's not moving which doesn't really move us forward. Need more clues..... Questions... 1/ If in 3rd gear, if you depress the clutch and try to rev the engine does it start working???? 2/ If you take out of 3rd gear and place in neutral does it start working? Clutch pedal up or down? 3/ What do you have to do to get the tach working again??? place in 1st or 2nd????? 1 Quote Link to comment
Veraciousreasoning Posted September 22, 2021 Author Report Share Posted September 22, 2021 2 hours ago, datzenmike said: A video will only show what you said that it's not moving which doesn't really move us forward. Need more clues..... Questions... 1/ If in 3rd gear, if you depress the clutch and try to rev the engine does it start working???? 2/ If you take out of 3rd gear and place in neutral does it start working? Clutch pedal up or down? 3/ What do you have to do to get the tach working again??? place in 1st or 2nd????? I'll check all this out today 1 Quote Link to comment
Veraciousreasoning Posted September 30, 2021 Author Report Share Posted September 30, 2021 On 9/22/2021 at 6:40 AM, datzenmike said: A video will only show what you said that it's not moving which doesn't really move us forward. Need more clues..... Questions... 1/ If in 3rd gear, if you depress the clutch and try to rev the engine does it start working???? 2/ If you take out of 3rd gear and place in neutral does it start working? Clutch pedal up or down? 3/ What do you have to do to get the tach working again??? place in 1st or 2nd????? When I push the clutch in and rev the engine it works normally. I opened up the dash and cleaned up the terminals and it seems to be working. I drove in 4th the other day and it noticeable moves now. 1 Quote Link to comment
datzenmike Posted September 30, 2021 Report Share Posted September 30, 2021 Maybe the dash flexes when the clutch is pushed and the contact is poor or a loose wire in the harness. 1 Quote Link to comment
Veraciousreasoning Posted October 1, 2021 Author Report Share Posted October 1, 2021 18 hours ago, datzenmike said: Maybe the dash flexes when the clutch is pushed and the contact is poor or a loose wire in the harness. Yea, that could have been it. It seems to be working now. I got it in 4th gear and got it to 3500 RPM which before it didn't move. 1 Quote Link to comment
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