weird tach problem
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=48959
Printed Date: July 03, 2025 at 3:39 AM
Topic: weird tach problem
Posted By: italnpimp59
Subject: weird tach problem
Date Posted: January 30, 2005 at 5:51 PM
im installing a 791XV in a 2005 E350 van and added magnetic door switches for the side door..but anyway the whole alarm is fine and i have everything hooked up but one problem, the starter output is not outputting anything when i remote start. and its not the hoodpin or brake wire or ground or anything, everything is hooked up fine. heres the weird part, when i disconnect the tach wire...in tach mode or tachless mode..it will crank, but of course not start cause tachless mode wont work on this vehicle and in tach mode, the tach is programmed..but when i disconnect the tach, it just cranks and thats it. i called DEI and we established that its a tach problem. i got the WHITE/ pink wire at the PCM just like the sheet said and it programmed fine to the unit. i even moved the tach twice and metered it..fine..programmed it..fine, but still no output on the starter wire till i disconnect the tach wire, then it cranks but wont start. this is the weirdest thing ive seen in a tach problem. ive seen bad tachs cause the vehicle to start and die, or just crank..but NEVER have seen it to cause the alarm to not output on the starter wire. im thinking its a bad brain. the customer is coming back wednesday so i was wondering if any of you have suggestions? thanks
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Replies:
Posted By: jrilla
Date Posted: January 30, 2005 at 6:11 PM
If you disconnect the tach, the van should still start, but since there is no tach source to tell the unit to stop turning the starter, the starter would over crank after the engine started. It sounds like you may have some wires mixed up. I don't see why hooking up the tach wire would have anything to do with the unit not trying to start the van unless it was seeing a tach signal even when the van was off.
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J Rilla
Owner/Installer
Posted By: italnpimp59
Date Posted: January 30, 2005 at 8:19 PM
i dont see why the tach would cause the starter to not output either, thats why im thinking its a bad brain. the wires arent mixed up though, i checked and made sure of that. i even took that center console off inside the van which allows access to the engine and tried a tach at the fuel injectors...still same problem. this is so weird. im thinking its a bad brain, what do u think?
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Posted By: italnpimp59
Date Posted: January 31, 2005 at 9:14 AM
anyone else got a suggestion?
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Posted By: italnpimp59
Date Posted: January 31, 2005 at 6:41 PM
i had this problem before i had the magnetic switch hooked up. the problem is in the tach wire. when it was connected, no starter output...disconnect the tach wire, and then output..but the vehicle wont run. some vehicles just wont work in tachless mode. and i know its the right tach wire. i got it in 3 places, metered it, and programmed it fine.
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