ISC Motor findings

[UlrichWolf]

Today, after two and a half years, my Palermo Gray car has a functioning ISC motor. Here's what had happened....

 

A few years back, I drove the car to Texas, to go to Turbo Addict's meet, and meet up with Russ. Somewhere between Turbo Addict's house, and the race track, the car sort of stalled on me, it was like someone had chopped the key and turned it back on real quick. It only happened once, and I thought nothing of it.

 

Well, on the way home, it started doing it often, and bad. So, I disconnected the ISC motor, having had a car that did this once before, and merged back onto the interstate laying rubber in two gears.

 

Is this how anyone else's ISC motors have failed?

 

A week ago, I bought an ISC motor from another member, figuring I might as well get off my duff, and fix it. Well, Maxzillian and I found out that not only was my unit fully repairable, but the one I got was in the same boat. Here's some things to check over.....

 

First, remove the rubber bootie covering the motor. There's a metal strap held down by two small Phillips screws that you remove, and weasel out of the way, and you can carefully pull the boot back to expose the wiring. There will be two wires soldered to the electric motor, make sure both of them are still connected. Of course, if you find one snapped off, resolder it on.

 

http://i723.photobucket.com/albums/ww233/UlrichWolf/Picture002-5.jpg

 

Next, look at your connectors. Take a close look at the wires coming out of the harness connectors. On both my original one, and on the one I was sent, there were two wires that had degraded, and on mine, one had snapped off, and on the replacement, they were on the precipice of failure. We figure that the snapped wire was what caused mine to act up, unfortunately, we did not make this discovery until after we chopped the connectors off to repair the other part. Maxzillian heated up the soldering iron, and de-pinned the connectors, and spliced in new wiring to replace what was quick-fried to a crackly crunch and snapped off, and whatever.

 

http://i723.photobucket.com/albums/ww233/UlrichWolf/Picture003-5.jpg

 

The green wire is for the nose switch, it was snapped off......

 

http://i723.photobucket.com/albums/ww233/UlrichWolf/Picture004-4.jpg

 

So, ISC motor repair is fully possible, and frankly, most issues are wiring related. This thing is hooked direct to the ECU, and it's either getting information, or giving information. And a wire touching in the wrong place can cause who knows what to happen.

 

This probably wasn't the greatest explanation, and I will add some pics in real soon to give a little better idea. This is also a good time to remind to actually diagnose a part to see if you can fix it before buying another one. I'm in NO WAY mad at the other member, he didn't know any more than I did that the wiring would be brittle, and it's no issue. If anything, I'm kind of glad, because now, I think I have zeroed in on a possible way to save parts that are getting hard to come by.

 

Tim

Edited August 3, 2009 by UlrichWolf

[Juggary]

Tim,

 

Good find! Until we find a direct replacement, finding a way to fix the one we have is always a good idea.

 

Please add photos to help explain your description.

 

Glad you fixed your ISC.

 

Gerry

[Shelby]

this ISC thing has been cover'd 100% many many times but it don't make any diff how many times it's type'd untill each guy see's fit to read and or follow instructions it does no good , life goes on as usuall untill one day oh my goodness that was not such a big deal after all,, i should tell every one about it,, da sorry charlie

[Truth]

Good find, but I ditched my ISC years ago.

[89PalermoSHP]

Tim,

 

Good find! Until we find a direct replacement, finding a way to fix the one we have is always a good idea.

 

Please add photos to help explain your description.

 

Glad you fixed your ISC.

 

Gerry

 

here is your direct replacement

http://cgi.ebay.com/ebaymotors/87-88-89-ST...d=p4506.c0.m245

 

get it on ebay or at autozone

[Shelby]

i have only seen one i couldn't fix,,after all it's only a bi directional electric motor ,, the ecu tells it what to do , 95% of the time it's a poor CTS signal that makes it screw up

[UlrichWolf]

this ISC thing has been cover'd 100% many many times but it don't make any diff how many times it's type'd untill each guy see's fit to read and or follow instructions it does no good , life goes on as usuall untill one day oh my goodness that was not such a big deal after all,, i should tell every one about it,, da sorry charlie

 

OK........

 

I searched. I didn't find anything. You know where I DID find something? In the wanted forum. There's been a lot of folks asking for these lately. 89PalermoSHP was nice enough to help drive my point home with an eBay listing for a $447 part. So, I beg your forgiveness for sharing with folks how to save a $447 part. I'm sure you knew all along how to fix the thing, but don't forget, I didn't just walk in here from the cotton fields. If it's not posted up, someone needs to post it up......we're car guys, and last I checked, Miss Cleo wasn't a member here.

 

I like you Shelby, but just because you have a disclaimer in your sig doesn't mean you have to live up to it.

 

Tim

[Juggary]

Tim,

 

Thanks for posting photos and details on how to troubleshoot and fix.

 

I'm sure this will help starquester's.

 

Gerry

[redzone]

the motors are available from electronics stores too

[Shelby]

OK........

 

I searched. I didn't find anything. You know where I DID find something? In the wanted forum. There's been a lot of folks asking for these lately. 89PalermoSHP was nice enough to help drive my point home with an eBay listing for a $447 part. So, I beg your forgiveness for sharing with folks how to save a $447 part. I'm sure you knew all along how to fix the thing, but don't forget, I didn't just walk in here from the cotton fields. If it's not posted up, someone needs to post it up......we're car guys, and last I checked, Miss Cleo wasn't a member here.

 

I like you Shelby, but just because you have a disclaimer in your sig doesn't mean you have to live up to it.

 

Tim

 

 

Tim i knew that was gona get your dander up but i did it for a reason,, to the point what you and others read or see on here depends entirely on what you click on and what you read , you most likely read more threads then some of the newer guys,, hell we go a lot of people that read only plain ol BS and thats as far as their learning goes ,,

 

i don't read every thread and every post on this site but i do check about 5 forums every day several times a day,, and of course on Starquest I-X i read every post .

 

now what happens when you read every post,, you read things that a lot of people don't , why cause they have never dream'd that one day they may have the same problem as some one else , the thought that all our cars are the same car basicly never cross's their minds,, what one has happen can and often does happen to others , then you have the my car is diff from every one elses,,it's white theirs is red and blue ,so i have to ask a new question " my car won't start" like what has been the problem 20,000,000 times before has nothing to do with my car it's white

 

right off we each have a copy of how to service and care for the ISC,,it's in the FSM,, we also have many threads a few of which should have been place'd in the FAQ but didn't for one reason or another,, but as a last resort theres always this

http://starquest.i-x.net/viewtopic.php?t=1...sc&start=50

 

i can't begin to count the number of times myself , Indiana , Mike C. and others have

type'd out how to's and what to do on or with ISC's , but in truth i do forget that every one does not read as many threads and posts as i do,,

 

for you new guys do you have any idea what you could have learn'd if you would have read EVERY thread in the VM and advMC forums over the past 11 yrs

i wasn't here that long you say ,, no matter the back page goes on for a long long time

 

Back to you Tim thanks for bringing up the ISC thing ,and posting the how to and pics , but the guys responces they have made points to the need for more reading and thread following then is being done , and some need to learn time travel is POSIBLE on the internet

[AzStar]

Well as a returning member trying to relearn my Conquest beast... frankly I find the search capabilities here abysmal! With every problem I encounter I try and search several different ways and often find nothing. Yet when I ask the question in the board, someone will post a link that takes me to just what I am looking for.

 

So while I don't deny that the information is probably in the electrons someplace... it isn't readily available to computer challenged folks like myself.

 

 

[Shelby]

thats why if you notice i said "back page" you guys aren't the only one that has trouble with the scearch funtion,, quite often i have to spend 30 min or more looking for a post in a thread , heck some answers may take hours to research and type but , no one pays the slightest attention to those details

 

take Wayne's SOS manuals,, it's taken him years to do but does any one give him one word of thanks , nope but theres a lot of guys quick to say he's a nut , well many of us are NUTs in one way or another

[Indiana]

I'd say dirty tip switch is more common than the broken wires but these old wires are so hard now from all the engine bay heat (usually) then one or two times unplugged and those wires break. Same for the TPS. I think I just mentioned that a couple days ago to someone to check the wires to see if they pull out. I've seen dead motors to or ones too weak to turn. When you get really into the details of anything you find you can fix many problems but it doesn't go much deeper than fixing this little motor. Now I don't think a slot car motor will work but maybe. The 86 I picked up a few months ago, the wires over on all the TB are still soft. Can't say why unless its just whether or not the car lived in a garage or not maybe. Like Shelby said, its hard to tell a new owner all the things that could be their issues its takes too long but they learn eventually if they don't give up.

[UlrichWolf]

Well, when Maxzillian removes his stuff to switch to MPI, we'll have another ISC, and we will go completely through it, and make a proper how-to.

 

I admit, by my standards, this one's not exactly up to scratch, but it at least gives an idea of where to start.

 

Tim

[IntercooledFlatty]

i do Shelby, from the starquest.i-x.net site:

 

I will say this PQ, i have learned MANY things from this site and appreciate the effort and work you have done here Cool , i am also putting the things i've learned to good use on my 85.5 Wink , Thank You

[Shelby]

not thanks to me,,thanks to Wayne

just said it he'l see it LOL

[moparetracer]

Today, after two and a half years, my Palermo Gray car has a functioning ISC motor. Here's what had happened....

 

A few years back, I drove the car to Texas, to go to Turbo Addict's meet, and meet up with Russ. Somewhere between Turbo Addict's house, and the race track, the car sort of stalled on me, it was like someone had chopped the key and turned it back on real quick. It only happened once, and I thought nothing of it.

 

Well, on the way home, it started doing it often, and bad. So, I disconnected the ISC motor, having had a car that did this once before, and merged back onto the interstate laying rubber in two gears.

 

Tim

I've been battling something that seems to be a similar problem for several months. I can drive my 87 Conquest around for about 20 minutes (almost to the minute) and it will go from running great to having no acceleration past 1700 RPM. The code it will throw is for the CTS (coolant temp sensor), so I replaced the sensor, the connector, and verified voltages from the ECU, but the problem still exists.

 

After reading about your symptom (stalled like someone chopped the key and turned it back on real quick) this is a symptom mine has just before it starts acting up as described above. After reading your post, I removed the ISC/MPS unit and looked for obvious broken wires, and found nothing glaring. I was able to activate the motor with a 9 volt battery, and the resistances checked out alright. Once I reinstalled it on the car, it still doesn't make any zip sound when the key is turned on, but for giggles and grins I wired it up, reset the ECU and went for a test drive that lasted over 50 minutes. No codes, no cut out above 1700 RPM, car ran flawlessly.

 

So my question is, what feedback does the ECU receive from the MPS that would cause the cut out problem, and how does disconnecting the motor (as you described above) make a difference? Does the ECU think that if the motor position isn't correct that the motor is still in some sort of cold start mode? Is there a chance that my ISC motor was stuck partially extended thus sending incorrect information to the ECU? I'm confused, but happy that I feel like I've isolated the component giving me months of grief, and I plan on replacing the ISC once I locate a good one, but in the meantime, is there a way to remove it entirely from the ECU feedback loop so this doesn't just randomly happen when I'm driving for more than 20 minutes? Again, how does disconnecting the motor address the issue? Can I simply trick the MPS circuit into thinking the motor is in its home position?

 

Thanks Steve

[CaliConquestAlex]

The original post is from 2009. I think you're better off starting a new thread next time.

[StarquestRescue]

The problem is usually the idle switch has failed or stuck in the idle position. So the ecu thinks the engine is revving to high with the throttle in the idle position and shuts the fuel off. Disconnecting the plug or plugs fools the ecu in to thinking the throttle is off idle so the car accelerates normally. However it will idle leaner and you will lose idle speed control with it disconnected, if it was even working, because the ecu will not know your foot is completely of the go pedal and go into idle mode................. Part of the ics system is a sensor that tells the ecu how far open the isc system is. This sensor can also be bad or stuck and send a bogus signal to the ecu which it may see as a reason to cut the fuel. The reasons as to why this cutout can be so maddingly random are not fully known...............It could be an intermitted problem with the switch or position sensor and or under some conditions the ecu ignores the out of range signals...........The parts are best checked on the car with a volt meter. The tps may also play a role in the conditions that triggers this. Edited November 13, 2013 by StarquestRescue

[Shelby]

what the ECU is looking for is the MPS voltage signal , some times the signal wires can be shorted and this depending on what wire is shorte can cause many diff things to happen

but bring this od thread back gives the new guys a chance to read and see more info about how to fix their problem with out some one haveing to redo all the pic takeing and writeing

[moparetracer]

So based on that feedback it sounds like I've probably stumbled on to the root cause of this particular symptom that's caused so much aggravation. This helps a bunch. Thank you both for responding to my inquiries. My car idles fair given it never changes RPM upon cold start, so thank goodness for living in Florida. I'll keep searching for a replacement ISC/MPS assy. Thanks guys.

[Shelby]

So based on that feedback it sounds like I've probably stumbled on to the root cause of this particular symptom that's caused so much aggravation. This helps a bunch. Thank you both for responding to my inquiries. My car idles fair given it never changes RPM upon cold start, so thank goodness for living in Florida. I'll keep searching for a replacement ISC/MPS assy. Thanks guys.

 

if you followed others replys 90% of all ISCs can be repaired with a little TLC

[moparetracer]

Thanks Shelby. I took the assembly apart looking for broken wires and checking for obvious wear on gears and such but nothing seemed obvious, so I'm sort of at a loss on what repairs I can make. I'm not afraid of wiring or soldering things, but I didn't see anything I would classify as "suspect". The car idles decent even when cold (thank you Florida), so if it weren't for the cruising issue after it's been driven for a while, I wouldn't even be messing with her.

 

If I just disconnect the ISC and the MPS, would I confuse the ECU and cause the same issue all over again, or would it drive normal except for idling and cold startup?

 

Thanks,

 

Steve

[Shelby]

that simple nose swt contact is the most important part of the ISC assy , if for some reason it does not make a good ground

the ecu does nothing to the ISC

another part that controls the ISC is the CTS , make sure it has good terminal connections and is working properly

old ohms should read like 2kto 5 k ohms and hot 300or so ohm 's

 

oh on the ISC nomaly it's just a little cleaning is all they usually need , most times you won't even see the problem

[StarquestRescue]

If I just disconnect the ISC and the MPS, would I confuse the ECU and cause the same issue all over again, or would it drive normal except for idling and cold startup?

 

Thanks,

 

Steve

It will drive normal, but not go into idle mode or fast idle on cold start up. But it does not sound like the fast idle part is working any way. Look closely at the picture. One T pin is in the idle switch cavity, the other in the motor position cavity. The plugs may not be in the same clip as your car, but you can tell which one has the male or female plug. .................................http://i237.photobucket.com/albums/ff45/StarquestRescue/ISC/DSC02871.jpg The idle switch should have either no voltage closed throttle or 12-14 volts with the throttle open. The motor position sensor, turning the key on with a cold engine. The voltage should rise to about 1.6, than after a short time drop back to about .9 volts. .................... Some years ago I made some crappy videos trying to show this.................. There is also a video where I grounded the idle switch and opened the throttle on the engine. If you listen close towards the end you can here the engine cutting out. It happens pretty quick because with no load on the engine the rpm rises and falls much quicker than in gear on the highway....................http://s237.photobucket.com/user/StarquestRescue/library/ISC?sort=3&page=1 ............................... I have seen some plugs that had the wires twisted together and shorted under the rubber seal as well. Edited November 14, 2013 by StarquestRescue