Voltage Issuses

Jeepxj94 · Jul 25, 2006

A few days ago I replaced my alternator and battery thinking this was why my voltgauge was reading so low. Afterwards my check engine light was still on and the volts reed 10 about.

I found out later that the voltage regulator is in the ECU pin 50 Alternator Output. 1991 and up have this type of setup.

Does anybody know how to fix this problem other than replacing the ECU?

If so pm me or reply to this.

Thanks

Scott

torfinn · Jul 25, 2006

Are You shure that the voltage regulator is built in the ecu? I find it hard to believe. The charging system is usually an autonomous system, not dependent of other systems. I think the pin that you are referring to is pin to make the alternator start charging. On older systems the charging bulb was connected between + via ignition key and the alternator. THe alternator has to have a + starting pulse in order to start charging. Another possibility is that the pin is to monitor the charging system in order to store codes in th OBD system.

regards
Torfinn

torfinn · Jul 25, 2006

How do you measure these 10V? Seperate volt meter over the battery? You are aware that the voltmeter in the dash is a notorious liar?

Torfinn

FRAM · Jul 25, 2006

torfinn said:
How do you measure these 10V? Seperate volt meter over the battery? You are aware that the voltmeter in the dash is a notorious liar?

Torfinn

Good to know as my voltmeter is all over the place from day to day but the alternator and battery is fairly new.

Matthew Currie · Jul 25, 2006

torfinn said:
Are You shure that the voltage regulator is built in the ecu? I find it hard to believe. The charging system is usually an autonomous system, not dependent of other systems. I think the pin that you are referring to is pin to make the alternator start charging. On older systems the charging bulb was connected between + via ignition key and the alternator. THe alternator has to have a + starting pulse in order to start charging. Another possibility is that the pin is to monitor the charging system in order to store codes in th OBD system.

regards
Torfinn

Crazy as it sounds, the voltage regulator is indeed built into the PCU (ECU, same thing) on 91-up XJ's. It is decidedly not autonomous, and there is no other regulator.

Matthew Currie · Jul 25, 2006

BAck to the original question, I would carefully check all wiring to and from the alternator, including the engine and chassis grounds, before zeroing in on the PCU. You can at least hope it's a bad wire or connector.

Jeepxj94 · Jul 26, 2006

Thanks for the Info. I checked all the fuses all is well. Some guy I know, Told me that 1991 and up have the voltage regulator in the ECU. I know in the ECU pin 50 is Alternator Output and that should read between 1-4 volts. If that doesn't work I heard then the alternator doesn't work.

I cleaned all the grounds and am thinking about rewiring the battery wires. My Optima is dead, so..I got to charge it. To get a ECU I know cost $590$ at the Jeep Dealer, so I hope it's not that!

Well thanks to all!

Scott

Jeepxj94 · Jul 27, 2006

Still have problems.. Checked everything..Wires, fuses, ....

Still have Voltage issuses.

HELP!!

Thanks Scott

Voltage Issuses

Jeepxj94

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torfinn

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torfinn

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FRAM

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Matthew Currie

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Matthew Currie

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Jeepxj94

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Jeepxj94

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