1987 240 Not charging? Dying / no start? / newer batt and alt

Heres a snippet from my post in my new build thread that sums up the issue: He told me it was having more problems with the alternator or battery or something and said it seemed like it wanted to die when he drove it last, knowing this I decided to get it as far home as I could, it?s worth noting when picking up the car it would not start on its own, once we hooked it up for a jump it still wouldn?t start, no click nothing, but with a bump start it got running and all seemed well, I started the journey home but noticed that as I began driving after a little bit the cars gas gauge and temp gauge started to drop, I had all of the other electric accessories off but lights were dimming as well. Then while driving down the highway around 15 miles into the trip the car began to stutter when the turn signal would be on, even when keeping throttle constant, there was a clear stutter whenever I turned on the signal, shortly down the road it just died and did nothing with throttle, I pulled it over and we got it towed the rest of the way home. Going off what I was told and what happened it sounds like some type of wiring issue with the alternator, so I?m looking for advice on how to get started fixing this, the batt light comes on the dash when the key is in on however also stays on with the car running, there is also the parking brake light on along with another light when the car is running. However, these all go off when under load. So today I started looking into it and could not see back of the alternator for the studs for wiring so I just ended up ripping it out since its pretty quick.

with this all being said this is where I?ll leave it off for now. I am stuck and any help or ideas on where to start looking would be awesome! I am definitely going to be trying to wire the alternator again tomorrow and make sure it was done right? I?ll also drop a link to the forum from the most recent owner that originally replaced the alternator and starter and then first started to have the problems.

Heres a picture I took of the alternator with the wiring before I yanked it:


Heres the linked post from P.O regards to his attempt to fix note he said it was fixed but that is no longer the case: http://www.forums.turbobricks.com/showthread.php?p=5939157#post5939157

Thanks in advance for the help!

See if there are any 940 Turbos in the U Pull & Pay yards around there. If there is one, and it has a Nippondenso 100 amp alternator, grab that, and swap it in place of the auto parts store reman Bosch 80 amp unit in there.

I'd also look for a replacement wiring harness from a 1985-87 240.

John242Ti said:

See if there are any 940 Turbos in the U Pull & Pay yards around there. If there is one, and it has a Nippondenso 100 amp alternator, grab that, and swap it in place of the auto parts store reman Bosch 80 amp unit in there.

I'd also look for a replacement wiring harness from a 1985-87 240.

Click to expand...

Are you thinking that whatever alternator this is could have gone bad?

You'd need to do some checks to tell.

Since you have it out just take it by a parts store. Most of them have a tester and they'll test yours for free.

Could be the alternator, could be a wiring issue of some sort. The warning light coming on is a good sign - that's part of the circuit that makes the alternator 'turn on'.

JohnMc said:

You'd need to do some checks to tell.

Since you have it out just take it by a parts store. Most of them have a tester and they'll test yours for free.

Could be the alternator, could be a wiring issue of some sort. The warning light coming on is a good sign - that's part of the circuit that makes the alternator 'turn on'.

Click to expand...

Right, I was doing some research on that with the D+ terminal on the alt and the exciter wire, though I'm still confused about it as this is the first time I've really done electrical stuff with a car. However, it is not normal for the battery light to be on with ignition correct? or is it likely the battery caused it to come on because it's actually so low?

Battery light has nothing to do with voltage (a low battery drops the voltage down), it's more of an indicator which way electricity is going in the charging system.

It's normal for it to be on when the key is on, but the engine isn't running. When the engine is running, it should go off.

When the engine first starts, the alternator needs a little 12V+ to come through that D+ terminal to jump start it. There are no permanent magnets - so until it gets some electricity in the field coils it won't generate any electricity (well... they can self-excite with some latent magnetism in a well used alt, but don't worry about that). So the ignition switch sends 12V+ through the bulb and on to the D+ terminal. That's enough to light the bulb, and kick start the alternator.

Once it's charging you basically have 12V+ on both ends of that warning light circuit, so the bulb stays dark.

Sometimes charging issues are that the warning bulb is burnt out, or the wire from it to the D+ terminal is broken or disconnected, so the alternator never gets that initial trickle of juice to kick start it. IN your case, it's a pretty good sign that end of things is all good if the light is working at all.

If you had a multimeter and it was still in the car, I'd suggest a few checks to narrow it down, but at this point it's most likely the alternator, and it's out already, so just take it by Autozone and see if they'll test it for you.

I recommend circuit verification before you waste time wrenching or driving to Vatozone.

Got a test lamp and a meter? They cost about the price of a gallon of gas each.


Test lamp on a disconnected exciter wire. Illuminate key on?

Add a redundant ground with a set of jumper cables. That's an easy check to see if it's a bad ground.

Auto zone was right down the street and I took the alternator in to have it tested, sure enough it tested bad, the brand on the old one is unknown, my guess is it just was bad idk, ordered a Bosch regulator, should be here tomorrow morning and I’ll throw it all back together and see if I can get it going! I’ll update from there and can continue to diagnose the issue if it persists!