Hello all, I have a 3.0 xtype that i believe is a late model 2004 according to fuse location for alternator within the engine compartment fuse box.
The wife was driving home from work and the idiot lights and signal lights etc in the dash started flashing like a Christmas tree. pressing on the gas pedal made the car slow and when she let off the gas pedal it sped up? she managed to get it into a parking lot nearby and it died. Would not start but cranked well.
When i got there in the truck to give her a boost, I thought the battery was dying and these electronically controlled cars act funny on low voltage. Car would not start with a boost either. I took the battery out as it was reading 11.9v and put in a spare i brought with me just in case. Still would not start. I put the old battery in again as it was now reading 12.35v after sitting out of the car for only 20 minutes?? The car started up! I closed it up quick as i could and tried to drive it home for further investigation.... i made it about 5 city blocks before it died again and would not start but cranked over well. I never experienced the flashing dash lights though.
I read some posts on here and did some checks on the alternator wires the next day and decided the original alternator was fried. i ordered a brand new alternator and put it in. it rn nd charged at 13.5v, yippee. I drove it around the block a few times and it was still good so i parked it for the night.
next day i started it up and it would not charge again, battery light in dash on again. i got disgusted and came in the house to check online again. went outside and started it up again and it was charging?? i went for a drive around the block and within 500yards the battery light was on again.

It's like the exciter wire to the alternator is not getting enough voltage to excite the alternator? With a battery at 12.4v with car off, when the car is started (battery light on) the battery in car reads 11.9v, across the battery in the car, at alternator big wire, at both cables to bottom sides of engine bay fuse box, on both sides of the 7.5 fuse in fuse box.
starting to think the GEM is screwy. Is the GEM the same as an ICU? i think i found it high up under the dash on the right side of car.

1) Are these resettable from within the car?
2) Are used ones needing to be reset by the dealer and if so can they do it off the car by the serial number?
3) Am I making any sense?

I have been up many wrong trees so far this week...lol

 

rdashton, the alternators on these cars rarely are the issue. From what you are describing, your problem is with the battery cables themselves. What we have found is that when the battery cables start to go, they will result in a low voltage condition of the car. What I want you to try is to put the battery on a charger and get it up to 100%. Now, with the engine cold, start the car and immediately turn on everything electrical that you can (seat heats, dash fan on fast, headlights, running lights, rear defroster). This will put a heavy load on the alternator. Give it 2 minutes or so and then open the hood/bonnet of the car and cup your hand over (NOT TOUCHING!!!!!!!!) the battery posts. Can you feel a lot of heat coming from one terminal and not much from the other? If so, you have just confirmed you have a bad battery cable (ie, the one that is hot is bad). if this is not the case, then we can do more troubleshooting. How are you with a multimeter? Just needing to know how detailed I need to get with my write up.

I think you are confusing a few things here when you are talking about computers in the car. The GEM module in the X-Type controls the electronics inside the passenger compartment. I can't say that I have ever heard of an "ICU" for in a car. The alternator is controlled by the ECU (engine control unit, also called ECM, engine control module). So, I would not worry about your GEM module. We will prove the ECU bad with some basic voltage checks if your problem is not with the battery cables.

 

battery cable test proved positive cable heating up under load. I changed out the battery to starter cable and big cable to alternator. No more hot cables. put back together filled with water and started up right off; no charging again. I did notice the battery at 12.56 with key off, 12.1 with key on but not running and 11.97 with car running. Mind you the headlamps do go on with key on. The alternator is brand new, I checked all the grounds i could find, and tested voltage at battery, alternator, starter, both big cables to engine bay fuse box....all read same voltage including the 7.5 blade fuse for alternator. All the same voltage running or off.

 

Here's the description of the charging system. Even though yours wasn't getting up to 15 volts - I have seen a lot of road side assistance condemn alternators as " overcharging " because it goes over 15 volts. With the X-Type, its normal to see a fluctuation from about 13.5 to 15.3. A lot of people don't realise this and end up paying money for something that isn't faulty.

As Thermo said, battery cables have been a well known culprit for the X-Type.

 

rdashton, based on what you are describing, it sounds like when you removed the cable off of the starter for the positive battery cable, you forgot to attach the other big wire to that post for the alternator. This is causing the alternator to have no where to send the power it is making, leading to the low voltage condition you are seeing. Otherwise, there is a new problem that has been created with the changing of the battery cable.

 

Actually, I replaced the alternator cable as well and at the same time as the starter to battery cable. OEM is a two into one cable. I replaced with two new aftermarket cables so as to save some cash. I hooked up the alternator cable direct to battery and the second shorter cable from the starter direct to battery.

So if I cround the U wire from the battery connector (which has 4 small wires in it) to ground I should see 13.6V to the battery? As it is all back together now and getting to the connector on the alternator is impossible, can i test the wire elsewhere, like the big square main harness connector beside the fuse box under hood?

 

Sorry I meant to say ground out the RG EN-49-1 to ground for 13.6V.

 

Also, i tried a different battery with same results. My battery holds a charge for three weeks without loss even though its 5 years old now. measured resistance through the new aftermarket cables (battery/starter/alt) and they read zero.

If I ground RG EN-49-1 while plugged into the alternator and engine running I should get 13.6V correct? if I do not then is the ICU screwed?

 

rdashton, you will need to access the engine control unit (ECU, what you call the ICU) to do the following checks. taking them directly on the alternator is best, but I also know accessing the alternator is very difficult. so, you may have a bad wire that is your issue unless you take the time to measure at the alternator.

I would first start with measuring pin 65 (orange wire with a green stripe) to chassis ground. You should be getting something around say 8 VDC if you have all electrical items turned off in your car when the engine is running. If this wire is up at 12.0 VDC (whatever your battery is at), then this is telling me that the ECU is seeing a low voltage condition and it is attempting to raise the voltage. If you are seeing this, then measuring at the alternator will be needed unless you are willing to take a gamble on installing a new alternator (more on this further down) and it potentially not being your problem. I would also say to disconnect the cable running to your alternator (engine turned off) at the battery and then insulating that cable. Then start up the car and do a voltage measurement of the cable to chassis ground. If you get something above 12.6 VDC (more than likely will be up around 15 VDC), this then is telling me that the new cable has a high internal resistance and that is driving what you are seeing. keep in mind that even something very small like a 0.1 ohm resistance (something smaller than most multimeters can read) can have a very big effect on the alternator cable. If you are getting 0 VDC on the alternator cable, then this is telling me that you are getting no field power. This is where if you were getting power on the field wire (Pin 65 above), then this confirms a bad alternator or bad field wire between the alternator and the ECU.

If you want to prove the cable bad between the alternator and the battery, what I would say to do is to very carefully remove any insulating tape you have on the cable with the engine running (making sure not to let the cable touch anything metal on the car) and then touch the cable to the positive battery post. WARNING!!!!!!! You may see some sparks come off of the cable when it touches. Be ready. If you can keep the positive multimeter lead touching the cable as you land it, that would be great. What you should see is if you are getting 15ish VDC on the cable, when you touch it to the battery, it will either stay up near 15 VDC and then decay down to 13ish VDC over a few minutes or will immediately drop to 13ish VDC. Either way, this will prove the cable good. If it drops to 12.0 VDC, you have proven the cable bad.

Repeating the voltage checks at the alternator will tell you what your problem component is. If you have 12 VDC at one end of the orange/green wire (Pin 65 at the ECU) and you have a much lower voltage at the alternator, then this is telling me that the wire between the ECU and alternator is bad. If you have the same voltage, then this tells me that the alternator is bad. Kinda like if you measure the voltage at the big lug coming out the back of the alternator (what you connected the new cable to) and you are getting 15ish VDC there, yet the battery will not go up to 13 VDC, then this would prove that the cable between the alternator and battery is bad. Measuring with the cable disconnected works only because you have no current flowing, therefore the voltage drop is non-existent. That is why when you connect the cable, the voltage drops (current is allowed to flow again).

If you need more info or help, let me know. I do wiring for a living and can figure out ways to get the readings that you are after.