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Arench, Master Technician
Category: Dodge
Satisfied Customers: 1490
Experience:  30-years experience auto and truck repair.
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B2500: 2005 Sprinter suddenly quit charging. Does the excitation

Customer Question

2005 Sprinter suddenly quit charging. Does the excitation voltage come from the instrument cluster?
Submitted: 2 years ago.
Category: Dodge
Customer: replied 2 years ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Arench replied 2 years ago.
Hello and thanks for being patient. The red wire goes to the battery and is hot at all times and the white wire goes to the cluster as confirmed with wiring diagram. When testing the white wire for voltage it must be disconnected from the alternator first and the engine started. When it's connected it will always show zero. Be careful working around moving parts! In most every case the alternator needs replacement. There are good deals to be had on for brand new Bosch alternators. I think there are three sizes, 120, 150 and 200 amp. You might see markings on the back of the unit that indicated the amperage.
Customer: replied 2 years ago.
Thanks for your response. You did not answer my question, so let me ask it in maybe a better way. Where does the alternator receive the excitation voltage from? (It appears that is comes from the instrument cluster, which would mean the 'regulator' is built into the instrument cluster). If that is the case and the excitation voltage is improper (or nonexistent) do I then need to replace the entire instrument cluster to get the alternator to charge?
Expert:  Arench replied 2 years ago.
The regulator is on the back of the alternator. The regulator receives its turn-on signal voltage from the cluster.
The cluster is not a regulator, it only sends the key-on signal.
The white wire must be removed from the alternator before you can measure the voltage on it.
Customer: replied 2 years ago.
Expert:  Arench replied 2 years ago.
You're welcome. Please let me know if you need anything further.
Customer: replied 2 years ago.
I have not dove under the car yet. This is a 'new' alternator (less than 6 months). It failed suddenly while driving under heavy load yesterday. I doubt that it failed already - although that is a possibility of course. I have had excessive parasitic draw (about 350ma) that I have traced to the instrument cluster and am suspicious of problems with the control signal from the cluster. If the alternator or regulator failed it is under warranty. Trying to muster up the energy to crawl under the thing on a 105 degree day and fiddle with it!
Expert:  Arench replied 2 years ago.
My experience is that you need a Bosch new alternator as a replacement because rebuilts and knock-offs like TYC do not last.
Good Lord are you in Arizona?
Any easy test is to tap the white wire terminal with a real test light hooked to positive. The little current passing through the bulb is enough to turn on the alternator.
Customer: replied 2 years ago.
What do you mean by "real test light"?
Expert:  Arench replied 2 years ago.
A real one to me is the kind with a light bulb inside rather than the new led type test light.
Customer: replied 2 years ago.
Thanks. I am in Walla Walla, WA, where it hit 113 on Sunday and is forecast to be in 3 digits for the next week or more.....
Expert:  Arench replied 2 years ago.
I had no idea it got that hot here. Sounds like Phoenix. I gotta check your forecast online now...
wow! what a forecast! zero chance of rain to boot.
Expert:  Arench replied 2 years ago.
How is the weather today?
Did you get that truck charging again?
Hope you have a great weekend.