ISC Adjustment

[livedsm4g63]

In dsmlink with both grounds selected my ISC only reads 9. I cant get it to move either way. I know it is supposed to be at 30. Any ideas why it wont move to 30 when im in BISS mode? All the coils are good. I took it out of the intake manifold and its not moving in or out when the key is switched to the on position.
Thanks in Advanced.

 

[gofer]

If it won't adjust and its not moving when you turn the key have you tested it with a multimeter?

YouTube - DSM ISC motor testing & Replacement

 

[sprmotohooligan]

I know on a 2G you aren't supposed to ground anything; I had a similar issue myself. You just adjust the biss SLOWLY while idling and streaming on link, and the ISC should adjust itself after a minute or two.

 

[livedsm4g63]

Negative. it doesnt move in or out. I opened it up one and i can turn it in and out by hand but it wont go in or out with a 6v battery hooked up to it.

All the coils test fine.

 

[gofer]

Here are the tests straight from the 1g Mitsu manual, make sure you are doing them correctly. If either of them fail then you need to replace the ISC...

ISC CONTINUITY CHECK (also the video above)

You must be logged in to view this image or video.

ISC SERVO CHECK

You must be logged in to view this image or video.

 

[livedsm4g63]

1 and 4 are week when i do that. However it still wont turn in or out no matter how its hooked up.

 

[steve]

First of all, when your in BISS adjustment mode the ISC only moves to it's default position and stays there. Once you leave BISS adjustment mode it should rehome (step in and out) when you power up the ECU like in the video below and track throttle position while driving. It's not going to be at 30 steps except perhaps at warm idle with the all the adjustment modes turned off.

<object width="640" height="390"><param name="movie" value="http://www.youtube.com/v/l7R3gf7SiAo&hl=en_US&feature=player_embedded&version=3"></param><param name="allowFullScreen" value="true"></param><param name="allowScriptAccess" value="always"></param><embed src="http://www.youtube.com/v/l7R3gf7SiAo&hl=en_US&feature=player_embedded&version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowScriptAccess="always" width="640" height="390"></embed></object>

 

[livedsm4g63]

The vibration hits once when i hook both up then it goes away. Should it stay vibrating?

First of all, when your in BISS adjustment mode the ISC only moves to it's default position and stays there. Once you leave BISS adjustment mode it should rehome (step in and out) when you power up the ECU like in the video below and track throttle position while driving. It's not going to be at 30 steps except perhaps at warm idle with the all the adjustment modes turned off.

<object width="640" height="390"><param name="movie" value="http://www.youtube.com/v/l7R3gf7SiAo&hl=en_US&feature=player_embedded&version=3"></param><param name="allowFullScreen" value="true"></param><param name="allowScriptAccess" value="always"></param><embed src="http://www.youtube.com/v/l7R3gf7SiAo&hl=en_US&feature=player_embedded&version=3" type="application/x-shockwave-flash" allowfullscreen="true" allowScriptAccess="always" width="640" height="390"></embed></object>

Alright, but while in dsmlink when i change the idle nothing happens. (Out of biss) It stays at the same idle. Should the isc see that change and change its position?

I'm going to take a wild guess that default is 9? However when I'm out of biss and idling with all adjustment modes turned off it reads anywhere from 0-120.

And there is no tracking in or out of the isc. Hooked up in the car or hooked up to a 6v battery. My old one doesn't do it and i bought one off here from a reliable source and they both just twitch.

 

[steve]

The vibration hits once when i hook both up then it goes away. Should it stay vibrating?

Alright, but while in dsmlink when i change the idle nothing happens. (Out of biss) It stays at the same idle. Should the isc see that change and change its position?

I'm going to take a wild guess that default is 9? However when I'm out of biss and idling with all adjustment modes turned off it reads anywhere from 0-120.

And there is no tracking in or out of the isc. Hooked up in the car or hooked up to a 6v battery. My old one doesn't do it and i bought one off here from a reliable source and they both just twitch.

Unless your applying power to the ISC windings in the correct order the ISC doesn't do anything but twitch. Since your ISC doesn't step in and out during power up, either the ISC is bad, the ECU has one or more damaged ISC circuits, or there is a wiring problem. Capacitor leakage will often damage the ISC circuit traces and if you find leakage under C106 it may short the ISC trace to +12v damaging the driver. A shorted ISC coil will blow the driver for that coil on the ECU.

If the ECU tries to step the ISC to control the idle speed and the ISC isn't moving the steps will tend to go to 0 or 120 and stay there depending on if the idle is slow or fast. The ECU doesn't actually know the ISC position only where it's asked the ISC go move to.

 

[livedsm4g63]

Say if the ecu is at fault. Where is the best place to get the work done? Or is there by chance a way i can order the part. I've soldered many times before so it won't be my first rodeo.

 

[steve]

Soldering is only one of the skills required. You need to know what to look for, where to look, how to really clean the board, how to repair any damage, how to test the ECU, and have a handful of parts from SMD capacitors to EMI filter arrays and M5269L drivers.

A year ago I'd say send it to me but I don't have time anymore to fix ECUs. Now I only recommend the guys at ECMTuning because I'm very picky about the quality of peoples work.

If you want to can verify the continuity of the circuit traces from the ECU pin to the driver.
The ECU pinout is available in the FSM or from ecuwiringinformation [ECMTuning - wiki].
The 1G Drivers are listed in http://www.dsmtuners.com/forums/art...585-troubleshooting-fried-ecu-components.html

Pin 1 and 7 are the two outputs from the M5269L. So you want to check IC105 and IC107 back to the ECU connector, all four ISC outputs.

 

[livedsm4g63]

Alright well I will get the ecu out after work and post it up, maybe with a couple of pictures if I find something bad. Thanks Steve. I'll check the continuity in those as well.

 

[livedsm4g63]

You must be logged in to view this image or video.

Alright, well i was able to figure it out somewhat and it through me for a loop because when you check continuity it shouldnt matter what side is postive or negative. So here we go.

Positive on 107, i get 2.79 M ohms on 3 except on pin 68 i starts at 1.01M Ohms and it starts counting down and keeps going

Positive on 105, i got zero for all of them

When I reverse the lead I got:
Negative on 107, Zero on three of them and pin 68 starts at 1.8M Ohms and is counting up.

Negative on 105, zero on three of them and pin 68 starts at 5.89M Ohms and it starts to count up real slow.

What are your thoughts?

 

[livedsm4g63]

You must be logged in to view this image or video.

I also found this underneath it all. It looks like it is directly underneath the top capacitor in this next photo

You must be logged in to view this image or video.

 

[Colt4G63 also]

You must be logged in to view this image or video.

That's a burned ISC trace. It goes from the bottom of the board to the top of the board, directly under that capacitor. I had to repair that exact same trace on one of my ECUs.

 

[livedsm4g63]

Nice, so whats the best way to repair this sucker?

 

[Colt4G63 also]

Nice, so whats the best way to repair this sucker?

I followed it from both places that it leads to, and bypassed it with a wire.

 

[livedsm4g63]

Would you mind taking a picture or pointing it out? I see where the one leads to on the bottom of the board. But where is the other location?

 

[gofer]

PM steve or send it into Tom and Dave over at ECMLink.

 

[livedsm4g63]

Or is the other location the burnt trace? So solder the wire in the burnt part? Then to where it leads on the bottom of the board?

 

[Colt4G63 also]

If you remove the bad capacitor you'll see another trace that eminates from right in the center of where the capacitor is, but doesn't connect to it. I would snap a picture for you, but the ECU I repaired is currently in my car.

IIRC I just wired it to the nearest junction where I could solder a wire to and complete the circuit.

You must be logged in to view this image or video.

This trace comes from the IC that controls the ISC. It appears to dead end here, but it actually pops out on the other side of the board. How badly the board is damaged will dictate how you will be able to repair the circuit.

 

[livedsm4g63]

So the capacitor is bad then I take it. Are they easy to find? Or should i just send it in for v3?

So that purple line is where your wire runs?and you just soldered twice on the back of the board? I tested that connection with my ohm meter and get 5.8M ohms. so i may be able to solder into the burnt end still because im getting a reading.

 

[Colt4G63 also]

No the purple line is the damaged trace that you need to fix. The cap is almost certainly the root cause for the failure. Generally when they leak they can reek havok on the board. That burned trace is right under a cap. How does the other side look?

Easy to find for me, I have an electronics store less than two miles from my house. I think the repair would cost less than a dollar to replace all the caps on the board.

Ps. Yes, if the board isn't that bad you may be able to melt solder back into the hole and repair the circuit. On mine I think there was over an inch of trace missing from the top of the board. I might have jammed a wire into that hole from the top, and ran a wire to the next stop along the damaged trace on top of the board.

 

[livedsm4g63]

I never took out the capacitor yet to see but there is some blackness I see around the one side of it. (on the top of the board)

 

[steve]

The cap in that location is the C106 I was talking about. When it leaks the electrolyte eats up the via (the copper tube that connects the top trace to the bottom trace) and often short it to one of the two pins of the capacitor. If it shorts the via to the ground pin you can just clear up the short, fix the open via and it will fix that ISC circuit. If the shorts to the 12v pin on the capacitor it either blows up the driver or damages it such that it can't activate that ISC coil and the driver needs to be replaced.

Before you can solder to anything all the corroded copper has to be removed. The solder won't actually bond to dirty, corroded metal.

Since the ECU sits with the connector facing down, anything leaking out of the capacitor is flows downhill as well as wicks into the surrounding areas by capillary action. You have to make sure that it hasn't flowed under the metal heatsink as well as under the small ceramic SMD capacitors just below C106. If there are any signs of corrosion (non-shiny) metals the part in question needs to be replaced.

The materials cost for the various capacitors/resistors/transistors is cheap. The electrolytic capacitors used to be less than a buck in volume. Things like the drivers and other ICs, when you can find them, can run more than lunch money. The major expense is in the time required to diagnose, clean, repair, solder, and test along with the experience to know how.