Ok, i have a 1998 XJ8 Vanden plas my lights including dash and radio display get dim and bright while driving. replaced alternator 2X and new agm Battery. 1st replacement alt overcharged Battery to 23 V. Thinking bad voltage regulator in alt. in 1st replacement. now new alt is acting up with light flicker. Any ideas.

 

Change your alternator supplier!

The symptoms are the volt reg inside the alt.

Have you had a meter on the alt? it should generate 13.8v - 14.4V.

 

thank you

 

23 volts! Amazing the rest of the electronics didn't **** the bed after that, or the battery didn't catch fire.

Symptoms do sound like vreg (I had similar symptoms and the Vreg solved it) - if you need part no's they are Transpo IN9218HD (OE: DENSO 126000-2640)

I've had better luck with the Denso if you can find it. My old alt burned thru a slip ring due to oil contamination, the replacement (junkyard) alt's Transpo vreg died after a few months of use. Pulled the Denso vreg out of the dead alt and stuck it in the newer one, and now voltage is rock steady even under revving.

 

Thank you thinking the same thing going to hook up a v meter on the car and see whats happening

 

Every city has a couple of guys who specialize in starters and alternators: take it to them and get it fixed with a lot less effort and frustration.

 

I recently had similar brighter and dimmer lights at idle and while driving. The changes were in irregular intervals, like what a bad connection somewhere would cause (a faulty voltage regulator would produce voltage pulsing in more regular intervals, I think). Anyhow, it turned out to be somewhat oxidised and slightly loose contacts at the main fuse box (large fuses) in the boot. After cleaning and tightening everything properly, the pulsing disappeared.

 

Thank you i will look at that and see what condition the connection is in