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Resolved 90 laser dead. help. >~<

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wolf alchemy

Proven Member
724
14
Mar 4, 2014
kouts, Indiana
1990 plymouth laser rs turbo
My car ran fine. Cell came on yesterday day a couple times. Not its acting like its possed. I try to start it and the rpms jump up and down, it sounds not normal at all some other gauges are hopping around. I think its the ecu since the doors don't lock together even though the battery has great charge. 11.4 volts. Help me please. D=[DOUBLEPOST=1410566029][/DOUBLEPOST]UPDATE:So I plugged in a fried ecu(supposed, old owner had no idea what anything was. Called a evo maf a 2g maf). But the car did exactly the same thing with the other ecu. So either my ecu is fried, or there is something else wrong with my car.[DOUBLEPOST=1410566068][/DOUBLEPOST]UPDATE:So I plugged in a fried ecu(supposed, old owner had no idea what anything was. Called a evo maf a 2g maf). But the car did exactly the same thing with the other ecu. So either my ecu is fried, or there is something else wrong with my car.[DOUBLEPOST=1410573295][/DOUBLEPOST]Help
 
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um, what makes you think 11.4 volts is anywhere close to "great charge"?

11.4 is dang near dead as a doornail.

replace the battery and check your alt. might want to check grounds and for any kind of parasitic draws.
 
Ok. Not perfect but my cars always can start without a problem on that voltage. Maybe its the car volt tester that you stick in the cigarette out let. I don't know[DOUBLEPOST=1410576974][/DOUBLEPOST]So because the battery is low its acting weird? Is that what your saying?
 
If it's not getting the voltage it needs it can cause all kind of problems. An example if you turn down the voltage on a fan it's not going to be running at it's full potential. My car has had idle jumps before and it was partly due to a damage honeycomb in the maf and the idle control valve. Post a video of it idling I'm sure people could better trouble shoot that way.
 
I can't start it. I'm driving a mustang in the rain and its my first time with red in rain. Going to work. I'll jump it tomorrow morning and get the voltage higher and try starting it.[DOUBLEPOST=1410579927][/DOUBLEPOST]I work 11pm to 8 am and I really wish the mustang had traction control.
 
Bear in mind the wiring harness is different on the 90 model. Not sure if it matters, but you would need to switch pin 6 & 14 if using a ECU from a different year.
 
There's stickers on the ecu. I'll post them after 8am. No idea where its from. What it goes to or what. Honestly not trusting the original owner
 
Take a VOM meter, set the thing to DC and put the leads across the battery with motor idling.

You should be seeing 13.8 to 14.5VDC at idle...and 11.4 VDC is spelling "alternator is toast" to me.

Anything different means a gone alternator - regulator is kaput inside the alternator.....

If you're seeing this 11.4VDC just from the lighter socket, still shows a charging system on the fritz.[DOUBLEPOST=1410587928][/DOUBLEPOST]If you can find a MD-128265 ECU, you'd be in good shape.

This ECU is 1990 FWD exclusive federal DSM.
 
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Take a VOM meter, set the thing to DC and put the leads across the battery with motor idling.

You should be seeing 13.8 to 14.5VDC at idle...and 11.4 VDC is spelling "alternator is toast" to me.

Anything different means a gone alternator - regulator is kaput inside the alternator.....

If you're seeing this 11.4VDC just from the lighter socket, still shows a charging system on the fritz.[DOUBLEPOST=1410587928][/DOUBLEPOST]If you can find a MD-128265 ECU, you'd be in good shape.

This ECU is 1990 FWD exclusive federal DSM.

I cant get it started and if I remember correctly. When it did run voltage was 12.7 on idle then spiked when on throttle between 13.6-14.3, but that was months ago.
 
Did you check the 80 amp alternator fuse yet?
also does the laser have a security system or remote door locks?

you probably should check all the fuses while your at it, the ones under the dash kick panel, and the ones under the hood/next to the battery etc. I also had the doors don't lock together syndrome on my 1g, it could be a fuse or [like in my case] a snapped wire under the dash that goes to the door opening relay.
 
I'm at work so I can't check anything till I get off. I'm going to see how much battery's are at Walmart. Unless I shouldn't buy a Walmart battery.[DOUBLEPOST=1410597108][/DOUBLEPOST]No security that I know of. And no idea on remote locks.[DOUBLEPOST=1410597200][/DOUBLEPOST]If the alarm goes off when I unlock it from inside when the window is down then I don't have a security system. Don't see a dash light for it. Unless its the weird orange Olympia collum looking thing.
 
I agree with what everyone else is saying but before you go out and buy a new battery you should confirm that is indeed the problem. Do a diagnostic test for both the battery and alternater to confirm that your charging system is functional before replacing anything. You will need a DVOM to do the following test. Note: A DVOM alone won't determine a bad battery.

Thing to check:

Battery - visual inspection, check cables and connections for croission and loose or broken/damaged wire.

Fuses - Check fuses, mainly battery and alternater

Alternator - visual inspection, cables and connections for croission and loose or broken/damaged wires.

- After checking everything perform a available voltage test on the battery to confirm that the source voltage is 12v or higher (If not then charge and retest) then a alternator perfromance test to confirm that your charging system is operating correctly. Start with a low output mode (engine rpm at 2000 rpm with no extra loads) then on a high output mode (with blower motor at its highest level, headlamps illuminated and rear defogger on while engine rpm at 2000rpm)

- Compare your results with your vehicles factory or aftermarket specs. Your results should equal or exceed (If aftermarket alternator is installed) your factory specs. Then your alternator is good. For the battery you may need a battery diagnostic machine to confirm if it's bad, unless it's a no maintains battery either way if it's bad it's not a repairable battery.

- I know it's long but I truely hope this helps
 
=D. That helps to know. And my car is at my town shop. The car had 13.4 volts while running and 12.8 withe everything possible on. I'm hoping bad battery.[DOUBLEPOST=1410617351][/DOUBLEPOST]I think I remember auto zone testing the battery and the ticket said just slightly on bad.[DOUBLEPOST=1410659682][/DOUBLEPOST]So here's the ecu. Post if you wanna see inside of it. The guy said it was fried but I don't trust him. And is it possible to put a evo 3 throttle body on our cars?
 

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the part number on the ecu refers to a federal 1990 manual trans dsm so you have the right ecu for your dsm...

Sweet. =D. I'm sorry if your tired of helping, but I do greatly appreciate it.[DOUBLEPOST=1410683954][/DOUBLEPOST]
Points to an alternator crapping out on you real bad .... the latter two numbers needs to be that all the time - both idle and throttle.
The alternated is replaced, but no clue on how much mileage its seen. I know in the 8 months I've had the car I put over 3,000 miles on it.
 
Read post No. 9 of mine above - I gave you the instructions.
It's not unusual for a recently installed alternator to still crap out.
Bought a reman from a shop and in three months crap out on me totally.
Got a replacement for free.
 
If you don't have the tools to test it, remove the alternator from the car and go to an autoparts store that offers free alternator testing, like Autozone, O'rielys, or Pep boys, and see if it's good or not, might also want to take the battery to them at the same time, my colt did the same thing as your car, it eventually turned out it was a dead battery.
 
Thanks every one. And the car is back to normal. Ecu is fine. Just compartment fuse. And the battery is still being normal at 12.7 when I always return to it, and charges with 13.2-13.9
 
Car runs great, still haven't had time to go to auto zone for battery or alternator, but I might this week on my days off. And when I say this I mean it. I love you guys who care enough to help. My first week on this site was met with hate posts and me just being yelled at. So have a wonderful day and I wish your cars the best.
 
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