tach on a 2003 gmc diesel

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=42162
Printed Date: July 07, 2025 at 7:39 PM

Topic: tach on a 2003 gmc diesel

Posted By: dfiddy
Subject: tach on a 2003 gmc diesel
Date Posted: November 03, 2004 at 10:13 AM

i need this wire for r/s, and right now it remote starts and dies, but with the key it is fine.

i am going behind the gauges so is it light blue, or the dark blue?

thanks for any help!

Replies:

Posted By: snguyen
Date Posted: November 03, 2004 at 10:17 AM

Looks like you need a bypass. What model of GMC do you have?

Posted By: dfiddy
Date Posted: November 03, 2004 at 10:27 AM

the starter is done, and it does start just not all the time, i used a 555l and python starter, the truck is a gmc 2500 hd with a duramax

Posted By: gus1
Date Posted: November 03, 2004 at 12:24 PM

Tach is white at the instrument cluster. Glowplug is dark blue.

Gus

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Wherever I go, that is where I end up......

Posted By: outtaluck72
Date Posted: November 03, 2004 at 3:59 PM

why not try voltage sensing if your alarm will let you. it will save you some time.

Posted By: johnnydi77
Date Posted: November 03, 2004 at 6:54 PM

the cluster comes out really easy so I think you should take it out and tach is right there...it's the only white in there.

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John J. DiStefano Jr.

Posted By: audiopro111
Date Posted: November 04, 2004 at 6:25 PM

remove the 4 corner screws of instument cluster they should be 7mm then pull cluster toward u in the plug thats connected to instrument cluster u will only find one white wire that is the tach wire

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AudioPro111

Posted By: slab42
Date Posted: November 07, 2004 at 9:50 PM

yeah, make sure you are using the "wait to start" wire mentioned above (glow plug)

also, i know the 04's have a factory feature where you cannot over crank the starter, or double start it. try putting the key in, let the glow plugs warm up, and crank it over, but don't turn the key back once it is started, leave it in the crank position for a few extra seconds. if the starter disengages without you turning the key back, then the 03 has the same feature. why does this matter? set your RS for tachless crank, (voltage) and turn the crank time up to the max... the truck will not allow it to over crank!