2002 Tahoe e-fans and volt gauge

[88lance]

Seen several posts about volt gauge bouncing around, but my situation seems a bit different since I just changed to electric fans, which is when it started.

So, '02 Z71 Tahoe, volt gauge always sits at 14 and never seems to move. I added electric fans and got rid of the clutch fan, and now when the fans kick on, the volt gauge bounces between 13-15 volts very quickly while the fans are on. When the fans clicks off, it stops at 14 and sits steady again.

At night you can actually see the fluctuations in the headlights and dash lights.

I have read that the alternator going bad is usually the cause for this, but since there was nothing wrong with the alternator before I added the fans, it makes me think it has something more to do with the fans causing the fluctuations, rather than something coincidentally going out right when I added the fans.

Anyone know what causes this?

 

[justirv]

Seen several posts about volt gauge bouncing around, but my situation seems a bit different since I just changed to electric fans, which is when it started.

So, '02 Z71 Tahoe, volt gauge always sits at 14 and never seems to move. I added electric fans and got rid of the clutch fan, and now when the fans kick on, the volt gauge bounces between 13-15 volts very quickly while the fans are on. When the fans clicks off, it stops at 14 and sits steady again.

At night you can actually see the fluctuations in the headlights and dash lights.

I have read that the alternator going bad is usually the cause for this, but since there was nothing wrong with the alternator before I added the fans, it makes me think it has something more to do with the fans causing the fluctuations, rather than something coincidentally going out right when I added the fans.

Anyone know what causes this?

Take a look at your RPO codes in the glovebox. I believe the '02's with fan clutch came with a 105 amp alternator. When they transitioned to e-fans in '05, the alternator got bumped up to 130 amp. This could explain the voltage drop or "instability ". Can I ask what e-fan harness you used, is it '05 OEM or 3rd party (like Nelson, etc.). I ask to see how you connected the AC fan on command, by tapping into the AC clutch signal, or adding a pin for ECU control?

 

[88lance]

Take a look at your RPO codes in the glovebox. I believe the '02's with fan clutch came with a 105 amp alternator. When they transitioned to e-fans in '05, the alternator got bumped up to 130 amp. This could explain the voltage drop or "instability ". Can I ask what e-fan harness you used, is it '05 OEM or 3rd party (like Nelson, etc.). I ask to see how you connected the AC fan on command, by tapping into the AC clutch signal, or adding a pin for ECU control?

Thanks for the reply. Fans and harness are from an '05. I tapped into the clutch signal wire under the fuse box.

I thought all the Z-71's were the larger alternator, I didn't know they didn't do the upgrade until '05, that may be my issue then.

I'll check my code in the glovebox this evening also.

 

[88lance]