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240 distributor terminal fault

was able to get my battery charged (must have had the manual charger poorly grounded on prior attempt) up to ~12.5V. re-installed, car started no problem - and the battery is ~11.9V with car on... 12.3V static. alternator is going out.

should i just sell this car? lord, it's had so many issues of late! what's that old hemmingway quote, about bankruptcy... very slowly and then all at once....
 
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It's probably just a broken alt ground wire, brushes, or exciter wire. Or alt.

Ground wire test= voltage drop test it OR run a jumper cable from the case to ground. With jumper cable from case to ground---13V? Engine running.

Exciter wire test= will a test lamp illuminate on it? Unplugged from alt. Key on.

Brushes test= inspect. It's two screws.
 
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Check the alt ground wire!

1. Loaded voltage drop. ( want less than 200mV)
2. Visual
3. Run a redundant ground
 
the ground is the spade connector from the main engine harness?

and this is the procedure: "Hook your meter's positive lead to the alternator output stud and your negative lead to battery positive post. Run engine at 2,000 RPM with all lights, blower motor, radio etc. on and check voltage reading on meter. Leave the rear defroster off during this check as it may create a unusually high read. An acceptable reading is .5 volts or less. If you have an out of spec. voltage drop, check connections at alternator and battery as well as for an use of undersized cable. Check the negative side for the charging circuit the same as the positive with your meter's negative lead on the alternator case, or ground strap if equipped, and the positive lead on the batttery negative post. Voltage drop on this side of the circuit should be .2 volts or less."

Charge light is NOT illuminating in the cluster. battery voltage is present at main alternator wire (bolt) with ignition off, bat volt present at spade connector with ignition on. i was thus far not able to trip the charge light by grounding the spade connector.
 
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The ground is an approx 10 guage BLUE wire coming off the back of the alt.

You could have a blown bulb in the cluster.

A test lamp should illuminate. Or, yes, the batt light should illuminate if you touch it to a good ground.


Yes, you quoted a voltage drop test. Go from alt case to a good block ground with the meter, start engine. What's the results? If it's 200+ mV = bad ground. If it's several VOLTS, or all the volts, it's a VERY bad ground.

GL. For a TB with such a recent join date you are doing well. Your skill level seems pretty good.
 
The ground is an approx 10 guage BLUE wire coming off the back of the alt.

You could have a blown bulb in the cluster.

A test lamp should illuminate. Or, yes, the batt light should illuminate if you touch it to a good ground.


Yes, you quoted a voltage drop test. Go from alt case to a good block ground with the meter, start engine. What's the results? If it's 200+ mV = bad ground. If it's several VOLTS, or all the volts, it's a VERY bad ground.

GL. For a TB with such a recent join date you are doing well. Your skill level seems pretty good.

got it, now that you mention, of course the red engine harness spade connector couldn't be a ground. will report back. i'll try to check the brushes today, too, but on first glance it looks like i have to remove the alt to get to them. OPS is in the way.
 
so my ground wire completely fell of my alternator... not sure how that happened??? it must not've been bolted down. does it matter which bolt I use to ground it?
 
so my ground wire completely fell of my alternator... not sure how that happened??? it must not've been bolted down. does it matter which bolt I use to ground it?

The adjuster bracket and alternator are suspended by rubber(or poly) bushings. This image shows it clearly. You can just see ground wire(blue) on the bottom of the case(stud with nut)


https://volvoforums.com/forum/attac...40-alternator-mounting-bracket-installedu.jpg

https://volvoforums.com/forum/volvo...not-charging-exciter-wire-68440/#&gid=1&pid=1

https://www.240turbo.com/boschalternatorlo.jpg


;-)
 
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I would replace that ground wire. After 10/20/30 years of engine bay heat and dirt and moisture it corrodes internally at the crimps.

Mine just failed on my 1991 740 and it looked ok.


After you reconnect it , one more time....... VOLTAGE DROP TEST IT. It takes less time than to write a reply.
 
alright, alternator is ground and here's the goods:

Battery voltage static: 12.48V
Battery voltage ignition on: 12.28V (charge light ON and other cluster icons illuminated)
Battery voltage engine on: 13.93V

after starting, idle was ~15Hz = 450rpm. Low. Strangely, as soon as I put my test leads on to do the positive charge volt drop test, the idle increased back up to the old high idle, ~64Hz = 1950rpm (!!!)

Volt drop values:
positive charge: + test lead on alt exciter wire, - test lead on positive battery post = 122mV with meter on DC, 0.026V meter on AC (assume meter should be on AC for this? only realized after taking DC measurements)
negative charge: - test lead to alt case, + test lead to negative battery post = 142mV DC, 0.016V AC.

so did i get the test leads right for the volt drops? if so, these values check out.

the idle is still high though. after revving above the idle, the engine drops almost to a stall, then jumps back up to idle. here's a video: https://youtu.be/ouPNhr-1bhY

i ordered a replacement for the duct-taped air boot so maybe that will make a difference. but maybe my IAC is just shot???

thanks everyone for your continued help, advice, and time. i appreciate yall.
 
142mV DC measured between alt case and battery negative is a good reading. That's less than 200mV. This means your alternator ground wire is doing its job. You really only need to measure to the block.

Your positive side test didn't make sense, but don't worry about it.

You got the alt charging. Good!

Now fix that air leak and reset your tampered throttle body. It's very common for people/shops to have messed with the throttle/idle screw on those LH2.2 cars when the problem is something else such as an air leak.
 
Since I've always been curious how things work, I took apart an old K-Jet IAC so that I could understand how re-assembling/re-aligning one wrong could result in mis-connected coils. I was surprised how it was built.

It's essentially a fixed magnet DC motor, with rotation mechanically constrained to only 90°, and the brush assembly being replaced with a rotating plastic contact holder and fixed flex springs (not quite sure what to call these).

The armature/rotor is built with 2 windings/coils and only 3 contacts, one shared between coils - 10ohms per winding in my case, but LH2.2 is ~20ohms per.



On the bottom left, you can see the rotary air control vane, with a limit pin sticking out further. The limit pin _should_ fit into the 90° slot in the air housing. If it goes elsewhere, the vane gets jammed and won't move.

On the bottom right, you can see the plastic contact holder. The contact holder is press fit onto the rotor shaft (firm hand pressure) and can be twisted around for factory alignment (not sure what they align to, but probably middle of the correct rotor contact). When assembled, the contact holder is pressed all the way onto the shaft and fully covers the rotor contact area.

The contact holder fits into slots in the end cap above and rotates back-and-forth as the vane moves. It's constrained to somewhat more than 90° of rotation. The 3 pin connector is hardwired to the 3 flex spring contacts.

On the left, the rotor shaft is supported by the air housing (metal on metal bearing); on the right, the contact holder is supported by the end cap (plastic on plastic bearing).

The upper right inset shows the end cap with the plastic contact holder installed. If you look carefully, you can see the arcs of the 3 spring contacts that will flex back-and-forth as the rotor moves. If the contact holder is twisted around, it will move to the next set of rotor contacts, resulting in the connector pins going to the wrong rotor windings.

For the OP: the IAC really isn't designed to be dis-assembled. Since you've seen bad measurements, it was mis-aligned at some point. It might have been permanently damaged at the same time. You should be able to gently move the vane back and forth through the air nipple, or you can twist the whole assembly quickly in your hand to get vane to move. There's no centering spring in it. If it doesn't move smoothly and easily, I'd replace the IAC.

-Bob
 
I was just following an article's suggestion on the positive charging volt drop test. i would think that that test - the positive charging side - would confirm that the exciter wire is good?

in any case, the only trepidation i have with the air boot is that, for years, that boot's been duct-taped and the idle has been fine. it was only after I cleaned the throttle body and removed it from the car that the idle got high.

still i will keep yall posted.

again - thank you all for your help!!! and especially for your time!!!
 
For the OP: the IAC really isn't designed to be dis-assembled. Since you've seen bad measurements, it was mis-aligned at some point. It might have been permanently damaged at the same time. You should be able to gently move the vane back and forth through the air nipple, or you can twist the whole assembly quickly in your hand to get vane to move. There's no centering spring in it. If it doesn't move smoothly and easily, I'd replace the IAC.

Thanks for all this good info! I will keep my eye on it. The idle character seems to change rather randomly, which makes me suspect it could be this IAC intermittently failing/mis-aligning.
 
it was only after I cleaned the throttle body and removed it from the car that the idle got high.

That involves bending the hose to get it off though. Could have finally cracked that dried-out old tape. Stuff isn't designed to be airtight in the first place.
 
New air boot is in and the idle is still high. Car started and idled around ~33Hz for a minute or so, then crept up to 60-63Hz. At the low idle (~33Hz), the car idled rough and the engine moved a good bit.

I sprayed with carb cleaner and could find no leaks in the vacuum lines nor gaskets. wiggling wires, I had a moment where the idle dropped when moving an engine harness grounding wire, but it was momentary and I could not repeat it even with several subsequent attempts.

high idle is only present in P and N. Putting the car in R or D, the idle drops to 'normal' level, though I couldn't put my meter on it to measure the Hz.
 
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i messed with the idle bypass screw on the throttle body today without any change to the idle character. grounding the IAC and backing out and re-tightening the idle screw did not change the idle at all.... neither did disconnecting the IAC altogether and manipulating the idle screw. nor did manipulating the idle screw with IAC connected and test terminal ungrounded...

additionally, i was unable to get any continuity reading off my TPS. i have it adjusted so that there is an audible 'click' when the throttle butterfly is opened via the throttle pulley. i was reading braille under the throttle body to get my test lead to the TPS terminals, but I wonder if my TPS is faulty.

Bentley is unclear to me on this in that they describe multiple steps beyond the two allen-screws on either side of the TPS: a lock nut, a throttle stop screw, throttle valve lever and throttle shaft are all present in the procedure, but are not indicated at all. so when I adjusted the TPS position, I loosened the two allen screws and turned the TPS counterclockwise until I got a 'click' immediately when the throttle opened, then tightened the allen screws down. but if i missed those other steps and parts, maybe my TPS is not correctly sensing the throttle butterfly position?
 
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