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1989 2.2L Turbo Charging issues

2K views 10 replies 2 participants last post by  19maserati89 
#1 ·
Hey all,

I have a 2.2L Turbo in an '89 TC that is having charging issues. Car sat for a few years and along with a laundry list of other issues it had the charging system is not right. When running it was throwing Alternator fault codes. Metered the battery and it was only at 12.2ish volts when running. Same with directly off the alternator. After sitting so long and being the original alternator I figured it was junk and swapped it out for a freshly rebuilt one. Same issue, only about 12.2v. Now I've gotten plenty of bad rebuilt alternators before right out of the box so I didn't think anything of it. I took it back and swapped it for another one. now this one is producing the same results. It's clearly not the alternator.....

Now I'm used to standard american V8 alternators that just have one + stud and wire. When it's running there's 13-14v on that wire which is directly common to the battery. What is the catch with these ones? It has 4 wires in that molded black box behind the alternator. I assume they are power, ground, and fields. But I would still expect to see more than 12.2v off of that main alternator power stud.

Who else has seen this? am I missing a ground or something simple that's broken in that connection?
 
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#2 ·
Another note on this topic. It’s my understanding that the ECM controls the ground on the field for these cars, with the ignition on I measure battery voltage of both of the field terminals on the alternator. It goes to 0 V whenever the ignition is off. Shouldn’t one of these field studs have battery voltage and the second one should be grounded which I could then test my ECM by shorting that stud to ground And constantly energizing the field.
 
#3 ·
Didn't I send you the Charging System Diagnostics and Wiring Schematic?

Power to the Field Terminal (DB Wire) is from the Ignition Switch so power will only be present with the Key On.
 
#4 ·
NAJ you're right. I'll be honest I had glanced at those when you first sent them and thought it absolutely required that DRBII unit to test, then I forgot you sent them to me by the time I posted this. I just revisited them again and it appears that the DRBII unit isn't critical. Infact I can't really tell what it does in the testing sequence. I'll try these tests tonight and see what i come up with
 
#5 ·
ok so I did these tests and it isn't looking favorable. Keep in mind I did all these without that special DRBII tool, which it never really explained the purpose of anyway.

A. 12v ignition power was measured on both field terminals- Move to step B
B. 12v power was measured on pin 14 of the 14pin SMEC controller - Move to Step C
C. Had to skip this step. Plug wouldn't come appart and I wasn't about to force it with everything else I've broken.
- Result 1 would've been to replace the SMEC
- Result 2 was move to step D
D.there was continuity between pins 11 on the 14pin connector and pin 14 on the 60pin connector
- Replace SMEC.......

No terminals were bent or distorted in any way. I cleaned them all just to eliminate old dried dielectric grease or corrosion as the culprit.

So it appear the only possible paths forward are to replace the SMEC.....Another can of worms for this car. Guess i'll have to dig into what SMEC I need to find and how to know it's good.
 
#6 ·
Two things...
1)The service manuals/service info is written for Chrysler Techs.
Any powertrain diagnostics flow chart will always refer you to the DRBII, they want you to use the scan tool even if only using the Volt/Ohm function of the scan tool so that it is already connected should you need to actuate or read data.

2)Check to see if the field control terminal is being pulsed, that is how the SMEC controls alternator output.
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If not the issue may very well be the internal voltage regulator in the SMEC, seems to be common and when there is a failure most bypass the engine controller as field control and install an external Chrysler voltage regulator in its place.

I have never done this but here is info, after reading the "how to" be sure to read the comments in the second thread listed, apparently there is some misinformation on the web about installing the mod that is cleared up by Dr. Johnny Dodge.





 
#7 ·
Unfortunately I left my oscope in the office when corona hit so I don't have it at home to accurately measure the pulses. On a side note I was able to find another SMEC online for $100 yesterday. They claim it is working as should but i know it's always a crap shoot when buying old electronics. I've got this car up for sale so I don't wanna dump too much more money into to it. But if this new/used SMEC doesn't fix it I guess I'll do that voltage regulator modification. Maybe by then I'll have my oscope at home to test the pulses.
 
#10 ·
I would think your next step is the voltage regulator assuming the field control wire is not open.
Thexton makes a Full Fielder for our cars, after searching it seems it is no longer available, a scanner will also allow you to control the field circuit.
 
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