my tach not working need help
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 937
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From: CARSON HILLS ca
my tach not working NEED HELP
08 z51 with hud. ok after driving my car around this morning i notice my tach was not working on dash or hud.i turned car off and on and on start up it does go up and down but thats it what do you think it could thanks in advance for any help could there be a loose wire or something
Last edited by mario7669; Feb 15, 2012 at 03:56 PM.
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 937
Likes: 0
From: CARSON HILLS ca
grounds look good is there like a plug on the eng.somewhere it seems like im not getting no signal because neither the tach on the speedo or hud work which is weird so im thinking theres gotta be a loose connector somewhere
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 937
Likes: 0
From: CARSON HILLS ca
still no luck i checked all fuses in eng.bay and floor board they all good i even changed out speedo with another one i had and nothing where else can i look i need to fix this to avoid getting ripped off by the dealer
Tech Contributor
Joined: Oct 1999
Posts: 41,055
Likes: 9,817
From: Charlotte, NC (formerly Endicott, NY)
The instrument cluster tach and the HUD tach both get their engine speed feed from the ECM. Circuit 121 (White Wire) goes from the ECM to the Under Hood Electrical Center and then to the displays. Here is a schematic showing the circuit path from the ECM to the displays and the connectors and pins used. 121 is to the left side.
Since both tachs are inoperative there is a good chance the fault lies between the ECM and the Electrical Center or in either the ECM or Electrical Center.
Bill
Since both tachs are inoperative there is a good chance the fault lies between the ECM and the Electrical Center or in either the ECM or Electrical Center.
Bill
Last edited by Bill Dearborn; Feb 15, 2012 at 07:29 PM.
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 937
Likes: 0
From: CARSON HILLS ca
i ended up taking my car to a local dealer and after 4 days of trying to find the problem i went down there today to see whats the hold up i talked to gm tech working on my car and he says its my ecm im wondering if he is just doing a 10 step and guessing what the problem is so now i gotta buy a new ecm hopefully that solves that problem is it possible the ecm can go bad and cause the tach not to work?everything else on the car work what do you guys think?
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Burning Brakes
Joined: Apr 2010
Posts: 1,075
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From: Asheville NC
i ended up taking my car to a local dealer and after 4 days of trying to find the problem i went down there today to see whats the hold up i talked to gm tech working on my car and he says its my ecm im wondering if he is just doing a 10 step and guessing what the problem is so now i gotta buy a new ecm hopefully that solves that problem is it possible the ecm can go bad and cause the tach not to work?everything else on the car work what do you guys think?
2nd Gear
Joined: Jul 2023
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