xk531 and viper 5101 remote start

I have a Viper 5101 that was installed by best buy.

They told me to get the XK531 but they were out. I purchased it.

It was installed, everything worked until it got cold about 2 weeks later.

Now all things work - except the remote start.

It will start when the jeep has been running and is warm, or been stored in a garage no problem.

BUT, and almost comically, if its cold, it will start, run about 8 seconds, die and retry a total of 3 times.

Now if I am in the vehicle, and once it starts I keep the gas going a bit so I'm basically revving the engine around 2.5k rpms it will stay running, but I let off the gas, it dies and continues its total of 3 restarts, 8 seconds then die.

I have redone the "tach" learning and it still has the same problem.

I dont know the firmware version of the xk531, and I can download the new firmware, but not sure how to install it. - heck dont even know if thats the problem.

Any ideas?

Its a 2000 Jeep Grand Cherokee.

The Viper 5101 system was purchased and install at BestBuy.

The XK531 module which was recommended to me by the first BestBuy guy (but they didnt sell them and were out of the other parts it seemed) was purchased online.

I did pay the bestbuy installer to install the XK531 (that was the standard module bestbuy used last year anyways).

I havent checked the wires yet though. ;)

Sounds like they did a virtual tach and didnt program the unit properly

suggest taking it back to them. that's the warranty is for, it doesn't cost you anything but time and you don't have to mess with it out in the cold

Are jeeps suppose to be not using the VTach? Or are you thinking the settings need reset for the VTach?

The thing that is so confusing is - it works if the engine is warm, but not if its cold.

try to ascertain how the reference was programmed... tach, V-Tach or voltage sense..... that will give you an idea of what to try instead....

there are potential reasons any of the three modes maybe be cutting it out when cold.....

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979

Thank you all for the responses.

My real question though I think comes down to this.

How is the Tach, VTach and such suppose to be connected? The install guide says - VTach. It *does not* tell me if a wire should be connected - but hints that it shouldnt be. I'm pretty ignorant of this stuff honestly, but its 100% possible I'm missing something ;)

We *have* redone the VTACH once already.

They say the module is bad - well one installer does - and he hates it - but I cant imagine this module being used for # of years being bad - and the remote starter kit was brand new. I really think its something "simple". (maybe I'm being hopeful <grin>)

It is not the module. It won't even let the car crank if it is. The problem is the tach.

If VT was used, no wires have to be connected, you remote start the car and you power it down WITH THE REMOTE ONLY to learn VT after the parking lights have turned on (20 seconds)

Otherwise if it is on VT and it is still acting up, have them run Tach to a coil or Tach signal. NOT a injector. This should be free because it states it in SOP to include tach hookup, and if they say otherwise tell them you will call corporate, that will change their minds.

yimke] wrote:

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Otherwise if it is on VT and it is still acting up, have them run Tach to a coil or Tach signal. NOT a injector. This should be free because it states it in SOP to include tach hookup, and if they say otherwise tell them you will call corporate, that will change their minds.

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best buy SOP actually states that virtual tach is perfectly acceptable. and for many of the viper units, the virtual tach has been more reliable than a tach signal

Well, after taking it back and explaining the above information, another tech was there. He said that he changed the tach and everything should be fine. I've tested now twice, and its starting. He said he changed how the tach was hooked up but just basically ignored telling me why (to his credit, (1) it now works, and (2) there must have been like 8 people waiting in line in the place for him. ;)

Feeling good its working. THANK YOU everyone very much for your help, I was pulling my hair out not even knowing where to begin in talking to this gentlemen on the issue. ;)

No problem, glad we could help.

And for SOP, technically it still says tach is included in the install for labor wise, and it hasn't been updated for virtual tach yet.

However you are right that virtual tach is essentially better because of learning over time adjusting to the vehicle's voltage. In this case though, if the person is having issues, and the tech was using virtual tach before, it is probably better to take 10 minutes to run tach and make a customer happy. I personally use VT for most installs.