When I start the truck the volt gauge drops down to below 14 volts and stays there until the pre-heater goes off then it comes up to 14 volts. I know this is normal from other sticky posts on DTR. But I also notice the RPM drops down 200 RPM and then goes back up, drops downs, goes back up until the pre-heater goes off. Is this also normal?

 

It is perfectly normal for your engines rpm to fluctuate along with the cycling of the grid heaters. When your grid heater is on, it pulls a considerable amount of electrical current. This added current draw puts a load on your alternator which makes it physically harder for the engine to spin resulting in your loss of engine rpm.

 

Thanks T-Breese. That makes me feel better.

 

Do you have the high idle enabled, if you do, this help the engine not pull down as much under a load.

 

Good question. How do you tell? Idles at 600.

 

on cold start after 1-2 minutes the idle speed will bump up a few hundred rpm. if you release the parking brake (remember I have a 6 spd) it will drop back down so that high idle is not engaged when driving. If you've parked the truck and set the parking brake, and it's cold outside, the high idle will kick up again on it's own....that's normal. Canadian trucks have this feature factory pre-set (cold white north, eh?). on US trucks you can get the dealer to set this for you.

 

Thanks, I'll check it out on the next cold morning. We will be though your area in June on the way to Fort St. John.