Viper 791XV remote start on 2004 Explorer

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=45797
Printed Date: May 10, 2025 at 9:33 AM

Topic: Viper 791XV remote start on 2004 Explorer

Posted By: jonkolo
Subject: Viper 791XV remote start on 2004 Explorer
Date Posted: December 22, 2004 at 7:41 PM

Hello, I installed a Viper 791XV on my 2004 V-8 Explorer.

My problem;

If the Explorer sits long enough for the engine to get cold, the remote start needs to make two attempts to start the engine. The first attempt cranks the starter too briefly to start the engine, and the second attempt is always successful. Again, this is only if the truck sits for an extended time period or the engine has time to completely cool off.

I connected the tach wire to an un-common fuel injector wire, since I was not able to sucessfully learn a signal from a coil wire.

During the first attempt, it seems like the Viper is getting a premature tach signal from the fuel injector. It must be enough to make the viper think the engine started, therefore stoping the starter cranking too early.

What can I do to solve the problem? Any help would be appreciated. Thanks

Replies:

Posted By: vinman75
Date Posted: December 22, 2004 at 10:05 PM

I had a similar problem on the same vehicle. Ever since I swithced to voltage sensing and took the tach wire out it hasn't been back.

Posted By: jonkolo
Date Posted: December 26, 2004 at 9:19 PM

vinman75 wrote:

I had a similar problem on the same vehicle. Ever since I swithced to voltage sensing and took the tach wire out it hasn't been back.

What crank time did you program? My Explorer needs to crank a lot longer when the engine is cold, so I expect problems with cranking too long or too short if I eliminate the tach wire and do that.

Posted By: Velocity Motors
Date Posted: December 26, 2004 at 10:50 PM

How long did you allow the vehicle to idle before you learned the tach signal ?

-------------
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Posted By: jonkolo
Date Posted: December 27, 2004 at 8:16 PM

Velocity Motors wrote:

How long did you allow the vehicle to idle before you learned the tach signal ?

I learned it as soon as the engine started. The viper installation guide said to do it within 5 seconds. The LED came on, just like they said.

I would really like to fix this problem. Any help would be appreciated. Thanks

Posted By: Scott35
Date Posted: December 27, 2004 at 8:26 PM

What he means is, did you let the vehicle warm up before you learned the tach signal?

-------------
Tacomacrew

Posted By: jonkolo
Date Posted: December 27, 2004 at 9:09 PM

Scott35 wrote:

What he means is, did you let the vehicle warm up before you learned the tach signal?

No, it was cold. ?????????