Charging/Starting issues

[tke395]

I'm trying to help a friend with her 84 grand marquis. She's had it for a couple of months and it started having "no-crank" issues. Alternator and battery had been replaced before she got the car, they are probably about 3 months old. Finally it was just dead, would not start or run. After I charged the battery it would start and run, but the charging system voltage was low. Pulled the alternator and took it to Advance Auto for testing. It tested good once and bad about 5 times so they agreed to replace it under warranty.

This is where it gets interesting. Advance had changed their stock numbers from when the original alternator had been purchased so they had to look up the new one by year, make and model. The one that they identified as the correct replacement (1st Generation alternator) did not match the unit I removed from the car. I thought maybe she had told me the wrong year and they were able to match it up. It appears to be a 2nd Generation alternator. I installed the new alternator and everything appeared to be OK. Car started and charging system voltage was good. At this point, I thought the problem was solved.

Three days later, it won't start without a jump. The wiring appeared to be in pretty bad shape so I tried to find a wiring diagram. This is when it became clear to me that things weren't adding up. The car is an 84, but the engine is a 5.0L with EFI. The charging system appears to match the 2G wiring diagram except the alternator output goes to the starter solenoid mounted on the passenger's side inner fender instead of the battery.

Any ideas on how I can get this sorted out? Are problems with the 2G charging system common? They had another alternator that had one of the plugs built into the alternator with a pigtail coming off of it. You had to cut off the wiring harness plug and splice the wires. Is this type of unit more reliable? I was hesitant to get this kind because it looks like the only way to get the alternator out is to cut the wiring.

I'd like to find a wiring diagram, but this seems to be a cobbled together system. Any suggestions?

TIA,
Eric

[miamibob]

Motorcraft made several alternators for this vehicle. Since it is a 5.0 that somewhat narrows it down. Does it have A/C or not? Was the original alternator 60/65 Amp or 100?? It is possible the previous owner had the incorrect alternator in and that is throwing you off. Take a look at http://www.rockauto.com and see what they show. Bobby

P.S. The voltage regulator could be an issue as can the connectors!!

[miamibob]

Another consideration is you will need to check all the charging wiring and connectors as you say the wiring is questionable. I know the later GM's have connectors near the coolant overflow/window washer tank so that is a good place to check, also!!

[Kodachrome Wolf]

Honestly, if you have to start re-running any charge wires, it might just be worth to upgrade to a 3G alternator. They give better power and reliability over the 2G alternator. A quick search should get you in the right direction.

[miamibob]

Honestly, if you have to start re-running any charge wires, it might just be worth to upgrade to a 3G alternator. They give better power and reliability over the 2G alternator. A quick search should get you in the right direction.

Not sure he wants to go that way but an excellent point!

[gadget73]

Can you get a picture of the alternator? In 1984, it would have had the external regulator setup. If its not that, someone changed it. If it has the 2 plug style with an internal regulator, thats the later piece of crap that 86-91 cars got. The harness is prone to melting down at the connector and the fuse links. Make sure that has not happened. Its also just possible the alternator is a dud. I've had them last a week before.

[Tiggie]

Have you checked for a drain on the system that could be draining the battery over a couple days time? Have had two 2g's that were battery killers. Both felt hot. One eventually caught fire. Oh boy.

[tke395]

Thanks for the replies. I don't have any pictures of the alternator and I can't get them right now since it's not my car. These links show the different alternators:

Here is the one that Advance looked up for a 1984. It does not match what was in the car:
http://shop.advanceautoparts.com/p/c...078a/5210127-P

Here is the one that matches what was in the car (2 plugs). It is the one I put back in the car:
http://shop.advanceautoparts.com/p/c...-10a/5210607-P

They had another one. I didn't get it and I can't find a link to it, but it looked like this with the pigtail permanently attached:
http://www.obbstartersandalternators...45-p-3492.html

The engine has the EFI cast aluminum intake. It looks like the engine was swapped at some point in time and the new one is at least an 86.

Thanks,
Eric

[pantera77]

Someone's done a SEFI conversion to it? Neat.

Honestly I'd just 3g swap it and call it good. Who knows what the PO did with the original wiring. Also, those 2g's are garbage.

[slack]

Have you checked for a drain on the system that could be draining the battery over a couple days time? Have had two 2g's that were battery killers. Both felt hot. One eventually caught fire. Oh boy.

+1 to this. It's amazing how fast a parasitic drain can kill a battery. I've had one in the past that would kill a battery in a day or two if the car hadn't run. Also, keep in mind if the battery went too low, it could have also killed a cell in it affecting the amount of charge it will hold. (esp. in the cold).

I know when my 2g goes, I'll be swapping for a 3g but if the 2g is working, it should be able to keep the battery charged under normal circumstances.

Also +1 to what Bobby said about the connectors. There are two of them, one by the alternator and one by the washer fluid bottle... that's if the PO did the wiring stock style. Although, seeing that they did an engine swap it could be "anything goes".

[gadget73]

Hm, well if someone did a SEFI conversion, you may be a bit on your own as far as particulars go. I would ditch that 2 plug thing though. They're just not amazing.

Anyway, check the wiring harness between the alternator and where it goes up to the fender. The fuse links are usually underneath the loom and thats where it will melt if its going to. 1986-specific wiring has those fuse links next to the solenoid, not under the loom between alternator and fender. The stock wiring on that type of alternator (and the older one too) does go to the starter solenoid. The battery should only have one fat cable that runs from battery to the solenoid. All of the rest of the electrical system ties in at that point.

A quick and dirty test is to just unplug the alternator and check for voltage at the connectors. You should get battery voltage at the two black/orange wires on the bigger plug, and at the yellow wire on the small plug.

[85crownHPP]

Yeah, it's possible you have a terrible hodge-podge of wiring someone did to make that alternator work. The charge wires go the long way around to the battery in those and aren't particularly easy to remove, so you might have some cobbled mess causing the trouble (if it's not a battery drain).
See if you can trace all the wires from the alternator as far as they go, look for anything that doesn't look 'original' and let us know what you find. They go underneath the airbox, so it will help to remove that.
If you still have the shiney-ish brass box about the size of a pack of cigarettes attached to the drivers fender well towards the front, that's the old external regulator. They would have had to make a couple connections into its wiring (to do it right), which is usually already full of crumbling insulation at the connector anyway.

[tke395]

Thanks everyone. Lots of good suggestions.