The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support Fuel Injector Clinic

Resolved 90 laser wont start

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

wolf alchemy

Proven Member
724
14
Mar 4, 2014
kouts, Indiana
I k ow I shouldn't post here, but all my DSM friends have no clue what's wrong. She cranks beautifully(sounds better than she ever has) I'm quite certain there's fuel being sprayed into the block(checked with q-tip) and there's no spark. I bought a new coil pack and no difference. I was told the cas by auto zone, but the one on the car is in way better condition than the other two I have.(looks to be a year or two old. Approximating). So how can I test my coil pack resistor. Or any one have any ideas?
 
A 1.5V battery is a AA battery. You would only need this to test the power transistor unit. The resistor box is for the injectors -- completely unrelated to spark.

Have you done the other checks outlined here for no-spark condition: How To Diagnose A No-Start? What are the results of your tests? Does the ECU show any stored codes? Does it light up for 5 seconds like it is supposed to at ignition switch "ON"?

Also...the Haynes manual doesn't show a AA battery. It shows this giant thing...
 

Attachments

  • IMAG0457_1.jpg
    IMAG0457_1.jpg
    199.2 KB · Views: 46
You sure that ECU turns on the CEL for 5 seconds?

It looks to me like the traces running to the MPI relay and from the Ignition switch are corroded to extinction. Perhaps there are jumper wires on the bottom of the board.

That's a typical "professional" half-assed rebuild. I used to see a lot of those when they failed again due to them not really cleaning all the corrosion and over time it eat something important.

At least it is a 90 style ECU.
 
I did swap a new good ecu in the car. Still, no spark. v_v beginning the think she hates me. All I need to do is test the power transistor box thing. If that's not dead.....I think I'll give up and need someone to come here and just fix it.
 
I tested my power transistor thing like my hyanes manual said, but on both tests for my cylinders. The needle went in the negatives. Should that be happening?
 
Since you're pretty certain everything else is okay, the ignition fuse seems to be the only thing that hasn't been mentioned. It's the left-most (as viewing the engine bay) fuse on the positive battery terminal. Pull it out and check it for continuity.
 
How do I test it. It looks fine. Correct?
Pull it out and check it for continuity.
Take your multimeter, turn it to measure resistance (Ohms, or the little upside-down horseshoe), and touch the leads to either side of the fuse. It should read just as -- or very close to -- if you were touching the leads together without the fuse.

No I didn't. It was hard enough to follow the book, since I only have wires and no clips. On the boom test. 1-4 went positive, but 2-3 went negative. Is that normal?
The FSM procedure has you checking for continuity on the PTU as well. Unless you're doing the test incorrectly, there should not be any sign change for the readings. The FSM test should be adequate to diagnose/test a really dead PTU. By all means, do the test luv2rallye posted to be absolutely certain the PTU works.

1990 FSM said:
POWER TRANSISTOR
An analog-type circuit tester should be used.

90 PTU Pinout
[1][2][3][-][5][6]​

No. 1-No. 4 coil side
(1) Connect an analog circuit tester (ohm range) between terminals "1" and "3".
(2) Connect a 1.5V dry cell between terminals "2" and "3", with the (+) terminal and the (-) terminal connected to terminal "2" and terminal "3", respectively.
(3) Normally, there is continuity between terminals "1" and "3" when dry cell is connected and there is no continuity when dry cell is disconnected.
*It shows the negative lead from the meter going to pin 1 and the positive to pin 3.

No. 2-No. 3 coil side
(4) Connect an analog circuit tester (ohm range) between terminals "6" and "3".
(5) Connect a 1.5V dry cell between terminals "3" and "5", with the (+) terminal and the (-) terminal connected to terminal "5" and terminal "3", respectively.
(6) Normally, there is continuity between terminals "6" and "3" when dry cell is connected and there is no continuity when dry cell is disconnected.
*It shows the negative lead from the meter going to pin 6 and the positive to pin 3.

If the problem is still evident after checking as described above, replace the power transistor

In sum:
For No. 1 and No. 4 coil, when terminal 2 and (+) terminal are connected, should get continuity between terminal 1 and terminal 3. There will not be continuity when the (+) is disconnected from terminal 2.

For No. 2 and No. 3 coil, when terminal 5 and (+) terminal are connected, should get continuity between terminal 3 and terminal 6. There will not be continuity when the (+) is disconnected from terminal 5.
 
Take your multimeter, turn it to measure resistance (Ohms, or the little upside down horseshoe), and touch the leads to either side of the fuse. It should read just as -- or very close to -- if you were touching the leads together without the fuse.


The FSM procedure has you checking for continuity on the PTU as well. Unless you're doing the test incorrectly, there should not be any sign change for the readings. The FSM test should be adequate to diagnose/test a really dead PTU. By all means, do the test luv2rallye posted to be absolutely certain the PTU works.



In sum:
For No. 1 and No. 4 coil, when terminal 2 and (+) terminal are connected, should get continuity between terminal 1 and terminal 3. There will not be continuity when the (+) is disconnected from terminal 2.

For No. 2 and No. 3 coil, when terminal 5 and (+) terminal are connected, should get continuity between terminal 3 and terminal 6. There will not be continuity when the (+) is disconnected from terminal 5.


I did the 90 power transistor test exactly like it's stated above. But when I did number 2 and 3 terminals the needle went negative voltage.
 
I did the 90 power transistor test exactly like it's stated above. But when I did number 2 and 3 terminals the needle went negative voltage.
You didn't -- or your terminology is wrong which isn't helping us help you. To test continuity:
Take your multimeter, turn it to measure resistance (Ohms, or the little upside down horseshoe), and touch the leads to either side of the fuse. It should read just as -- or very close to -- if you were touching the leads together without the fuse.

The FSM procedure has you checking for continuity on the PTU as well
. Unless you're doing the test incorrectly, there should not be any sign change for the readings.
You are not checking voltage with the PTU test.

Did you check continuity of the fuse?
 
It's not. I'm being precise with what I'm saying. On the 1-4 coil test on the power transistor the needle went this way
You must be logged in to view this image or video.

On the 2-3 coil test the needle went into the negative zone
You must be logged in to view this image or video.


Hopefully now you understand.
 
Try reversing the leads on the 2-3 test to see if you get it to go the other way.

Did you test the continuity of the fuse?

The fun part is just beginning if you're looking for the easy way out. If all of the hardware components check out, it is going to be a wiring issue.
 
I'll try that, but if it is reversing the polarity. Could that be my problem of why theres no spark. And not yet.
 
Pic is dark. Are you checking resistance? Thats why brian said your terminology was bad. You cant have negative resistance. Cant read how your meter is set from those pics.
 
Ah. It works! Which means the power transistor is fine.....and the fuse is fine.....cas looked brand newish, and I tried a second one, but still no spark.
 
Does the car have an after-market security system installed, or perhaps maybe a kill switch, it may have went haywire?

You can also unplug the ecu connector and then go under the hood and see if you have continuity to the all the wire connectors related to the ignition system under the hood, and see if they trace back to the ecu pins if there is a damaged wire this will help track it... pin outs link http://www.dsmtalk.com/forums/attachment.php?attachmentid=17178&d=1423513973.
 
I have a possibly stupid question. If I did the timing, but put the cas on qmwith the fin spun 180°. Will it start if I remove it and set it correctly. Or will I have to rotate the engine, back to the correct tdc, then fix the cas?
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top