djgrayxj
NAXJA Forum User
- Location
- West Covina
Alternator overcharging problem.
- Thread starter Talyn
- Start date
- Location
- on the beach in Ocean View, VA
did you, by any chance, notice what type of machine each store was using?
My experience with the "old" Mini-Tune tester (industry standard until a couple years ago) has proven time and again that unless you reverse the field connections and test the circuit both directions, it can miss a shorted circuit in one direction.
If a new alt. solves everything (and it sounds like it will), I would be interested in getting the failed alt. from you to use as a teaching tool in my store. I'm sure I can find a core to send you for the core charge if you're willing-- lemme know via P.M.
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
The kind aren't worth a damn. Lol. They all looked like newer machines. I figure they were just checking output, not that there is output when not called for.
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
Article doesn't help as it address a no charge condition and it is inaccurate:
The PCM still controls the ground side on this vehicle.
Last edited:
O-Gauge Steamer
NAXJA Forum User
- Location
- Colorado Springs, Colorado
Talyn, would it help if I ran the same frequency test on my 98 for comparison? I assume you set the DVM for DC Hz to count the pulses? Let me know either here or via PM and I will run whatever check you think might help.
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
I don't know if it would help in this case but it would be interesting for comparison. I want to test my 2000 XJ and 95 ZJ, but I haven't had time. On my XJ the system is a bit different as both of the field wires come from the PCM.
As for the setting, my DMM has a Hz/Duty % setting. I can switch between those two settings, but no other options are available.
As for the setting, my DMM has a Hz/Duty % setting. I can switch between those two settings, but no other options are available.
Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
New alternator is in and it looks like it is fixed. I'll take it for another drive later just to make sure.
I compared the new to old alt. Between the alt case and the field terminals the old one was showing 2.130 k ohms. The old one also showed continuity at times previously, which is less that 30 ohms on my meter. The new one showed an open circuit.
The shop that installed the old alt at the beginning of the year told her that she needed a new PCM. I was told that her original alt failed with no charging, they installed the faulty alt which over charged and blamed it on the PCM. It looks like they also lost one of the alternator mounting bolts as they replaced it with a bolt that was a) too short, b) SAE thread, and c) wasn't tightening.
I compared the new to old alt. Between the alt case and the field terminals the old one was showing 2.130 k ohms. The old one also showed continuity at times previously, which is less that 30 ohms on my meter. The new one showed an open circuit.
The shop that installed the old alt at the beginning of the year told her that she needed a new PCM. I was told that her original alt failed with no charging, they installed the faulty alt which over charged and blamed it on the PCM. It looks like they also lost one of the alternator mounting bolts as they replaced it with a bolt that was a) too short, b) SAE thread, and c) wasn't tightening.
