cel came on, check for code and 42 and 47, my alt does not charge for the first 10 to 20 min of every cranking cycle and then charges fine. what should i check? and thanks for any ideas. Code 42 is an open or shorted condition detected in the auto shutdown relay circuit. code 47 battery charging system voltage too low.

 

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1995, 3500, 4x4, auto, 250,000 miles ctd

 

the asd relay is located in fuse block under the hood. the voltage regulater is controled by the pcm.

 

check battery connections where they connect to the battery need to be clean and tight. make sure your batterys are charged good. check the wiring to alt and connections. check drivebelt. check alt mounting bolts for tightness. run engine and check alt for abnormal noises. battery voltage with engine off should be 12 volts it should be 14 to 15 with engine running.

 

check all the above and everythging is working right. the alt still will not charge for about 10 min of every starting cycle.

 

well I just had the same problem, go with an external voltage regulator. cheap easy and works great. Do a search there are lots of threads on it. I just towed 8k enclosed trailer and had a cabover camper. The same alternator that coudn't put out more than 13v (when working) ran everything and charged the camper batteries, never fluctuated more than .2v off of 14.5V. I would say it is a good mod. But the check engine lights stays on, I can't figure out a way to trick it off.