Engine code 41 remedy?

Fault Code 41 Synopsis Description: Alternator field control circuit open or shorted Power loss light: Off Limp-in mode: None

Possible Causes Bad connection or wiring - Check the wiring and connections between the logic module and the power module. Clean and regrease any corroded connectors with dielectric grease and repair any shorts. Bad voltage regulator circuit - See Diagnosing Your Charging System

Diagnostic Method Trigger Parameters

- Near 0V or near 12V not detected when the field coil driver is turned on or off, respectively Results If Component Fails Fault code 41 is stored. If the condition persists, it will eventually result in a fault code 46 or 47.

In article , Pond Scum wrote: # #Anyone know what the most common fix for engine code 41 is ('93 ZJ)? My #alternator is not putting out any output. Is it typically more than just #replacing the alternator? I'm trying to get this vehicle running so I can #give it away to a relative, so I'm hoping it doesn't turn out to need #anything expensive. #

Is this the original alternator?

/herb

Herb Leong proclaimed:

Dunno about the 93 but on the later ZJ, the voltage regulator is not in the alternator, it is the engine control computer.

If the 93 is the same, there is a way to check quickly, but you need to pull the control wire and I would be hesitant to go thru the details unless you have a factory manual or like the smell of magic smoke.

First make sure you have a fully charged battery and the cables to the alternator are squeaky clean, shiny, no corrosion, and tight. Also make sure the connection to the body right near the battery is squeaky clean and tight.

IF your 93 is the same as the 95, the way the PCM controls the alternator voltage is by applying and removing a ground to one of the fields.

Your diagnostic code indicates [among other things] that the PCM is having difficulty pulling that field down to ground. There are a number of reasons for this including a blown PCM, but it is just as often krappy krysler wire that even Lucas would be ashamed of.

I wouldn't suggest trying to ground the field yourself without the aid of a FSM diagram and perhaps a buddy familiar with power electrics and definitely pull the PCM wire.

A local shop might be willing to see if they can tell the difference, if it is the PCM, junkyards work as does eBay. The alternator isn't that expensive either.

Lon did pass the time by typing:

On the 93 the regulator is in the computer. Grounding causes the alternator to charge the battery, but you have to be very attentive not to put out over

Yep. 93-95 are all the same setup. 96-99 is slightly different but still used the computer.

Code 41 is "an open or shorted connection was detected in the generator field control circuit"

(always disconnect the battery when working with the alternator or computer)

I'd check the wire first. The alternator output terminal has battery voltage on it at all times.

on the back is a 20 gauge, dark green wire. This is the regulator wire that runs to the computer. (box on the firewall behind the overflow bottle)

This could be a dirty connector on the computer. Bit of a pain to deal with. You have to take the overflow bottle out, then remove the plug, take the computer off, clean the whole thing with contact cleaner (that is safe for plastic). Put some dilectric (sparkplug) grease on the connector, and reassemble. Just don't crank too tight and don't use the bolt in the connector to suck it on. That will crack the computer. just push the connector on, hand tighten the bolt, press the connector again..etc..

Having a computer fault is low on the list, but given the cost of both part it may well be worth it to have a dealer check it out.

Some stores will check alternators, but you have to remove it and bring it in.