Shift Light Installation

[jcaspar1]

I recently installed an Armtech shift light per the Illustrated Viper Cookbook and am having a problem. The shift light works well for a period of 6 to 24 hours but then seems to drift about 250 revs. For example if I set it a 3000 it will work well for awhile then start triggering at 2750. It will then continually trigger at 2750, then back to 3000 after awhile. I replaced the unit so I don't think that is the problem. I have the trigger lead connected to pin 1 of the Powertrain Control Module C3 (Ignition coil No.4 driver). To be sure the connection is good I soldered it with no luck.
Is there a better site to tap into for the RPM trigger? Any idea why the coil trigger is unstable?

Thanks

 

[jcaspar1]

Unfortunately it jumps between the two settings. Just interested if anyone else uses a shift light and if they used a different trigger for the rpm sensor.

 

[Jack B]

I am using an Auto Meter unit. The light is triggered by a power supply module that I connected to the Gray wire at the factory tach in the dash. For that those that want an unobtrusive shift light, the Auto Meter model 5310/quick lite can be held on the column with a 1" x 1/2" piece of velcro.

I don't see how anyone with a Gen I can see the tach when racing because of its offset in the dash. This is unlike the Gen II that has the tach centered. When you buy the Auto Meter you must send it to the factory for them to change the calibration from its base 8 cylinder setting. There is no charge and the turn-around is only about a week. You can also take the output of their power supply and drive an accessory relay and trigger both turn signal lights if you don't want the light exposed. Summit Racing is a good source - they ship next-day automatically.

 

[Tom F&L GoR]

I have the Autometer light, but use the stock piece and RPM chips. You'll have to re-calculate what chip you want, since you have two more cylinders, and the light counts plug firings. For instance, to set the light to go on at 5300 RPM, use a 6600 RPM chip, i.e. 10/8's higher. Besides, it's funny to see faces when they see a 6600 or 6800 chip stuck into the dash of a 488 cubic inch engine...

 

[jcaspar1]

Tom
Thanks but the Armtech shift light doesn't use pills. You simply rev the car to 1/2 your intended rpm and push the set button. Doesn't matter how may cyls you have as it just triggers at twice the rpm (up to 50k rpm).

What trigger did you use for the rpm sensor when you installed it?

 

[8AVETTE]

Jeff, Does Armtech have a web site?

Thanks.

 

[Tom F&L GoR]

Hi Jeff,
It's an Autometer 5340 on a shortened "foot" so it's below the steering wheel rim. The trigger is the tachometer signal wire from the ECU; G21 20 GY/LB* (circuit G21, 20 gauge wire, gray with light blue stripe.) I hunted for it under the dash and used a clip-on splice.

Forgot to mention that by using the 8-cylinder pills, you actually can get finer tuning of when the light goes off; changing from a 6600 to 6800 "pill" changes the actual RPM from 5280 to 5440, or a 160 RPM difference.

 

[jcaspar1]

Thanks Tom, That's what I was looking for! I will give that a try. I wish I had gone with the autometer but I thought the ability to set it at any rpm would be an advantage.

Don, They don't list one in their instructions. I was thinking of calling them but they are in England and I figured they may not have alot of experience with Vipers.