95 SC throwing codes - intermittent running problems

I'm out of my depth on a '95, but I do know that on later models the ABS/TC motor isn't supposed to charge up until you hit about 12 MPH... I feel it do so all the time if I ride the brake as I pull away.

Hmmm....

Jeff, the problem I'm having is the traction motor should not be running at all in this condition, as there is no signal from the vss (vehicle speed sensor) nor the hub speed sensors to tell it that the vehicle is moving. I think you're hearing the air pump for the auto leveler, in some cars it sounds just like a trac control motor. But I am not there and so I don't really know. Adding to that the fact that you're angry/frustrated, complicates things a little.

Let me review what you've posted already and see if I can be of any help. In the meantime - how long have you owned this Riv? I'd like to understand what maintenance & repairs have been done on it so far. Will keep me & the others from recommending things that either you already did or won't help, and might point out some things that ought to be done to save you from future headaches.

My comments will be a bit disjointed but will quote your earlier posts.

Albertj

Abaddon wrote:

If you determine that those wires are the problem, the wire repair kit (ICM harness) would be perfect. I'd check with Morad first. Just send 'em an email describing what you need (ICM harness). They reply very fast.

Don't try to "patch" the wires. That bend in the harness at the ICM doesn't have enough space to house crimp connectors or scotch locks. Yes, you can do it that way, but you will be adding even more stress to that bend. Get the new (or used) harness and splice it in about a foot down where it's straight and there's room (if that's the problem).

Thanks for the link Alby!

OK first things first - if you told Morad you needed the ICM harness, how'd you get an engine wiring harness without the ICM wiring, and what did you splice together that would work?? That is, if the ICM plug/wiring was a problem, putting the old plug/wiring onto the replacement harness -- I don't get it.

So first thing I think is you might want to look at what you communicated to whoever you bought that harness from and if they made a mistake point it out. I am sure that if Ed M made an error he will make it right if you point it out. IF he did not make an error I have to rely on your harness splicing, which is OK but might be something to recheck.

Albertj

jeffyd123 wrote:

OK took it for a drive... started right up but threw a CEL at me.

drove well but seemed to have a slight miss.

gonna grab the code and see what else she wants.

I would very much like to know what code triggered the CEL if you can tell me.

Albertj

jeffyd123 wrote:

WEll Heck...

Got in the car this morning and it wouldnt start. It stumbled then conked out and wouldnt fire up.

Any ideas?

thanks

When the crank sensor fails, first it quits 'bad warm' - you'll go for a drive then park the car, if you try to restart while warm it won't start and won't throw a code. As the problem worsens eventually the car won't start at all.

The crank sensor is a hall effect sensor and has some (relatively simple) circuitry built into it. The heating and cooling it does by the engine eventually causes the connections to open intermittently (when warm) You can verify this failure by checking the sensor with a multimeter for continuity - then heat it (with heat gun/hair dryer, one post on the internet showed dunking it in boiling water) and it opens (resistance goes infinite).

I am wondering if a failing crank sensor is one of the problems. Again, it won't set a code, and if if is a problem at the same time as something that *does* set a code it could cause much confusion.

So the queston is, does your car have more than 70,000 or so miles on it and has the crank sensor ever been replaced? Do tell.

(this will be it for now)

Albertj

hi albert

the traction control motor is whats cycling after i hook up the battery and turn on the ignition... Its coming from the front of the car and Im familiar with the sound of it.

I bought the wiring harness expecting to get the ICM harness too but they didnt include it. I put my old harness back in as it looked like it was in good condition. Im going to try to return the new harness as I dont need it. I cleaned the plugs that were oily on my harness before putting them back in.

I rebuilt my ICM harness and pulled it back out and double checked the continuity of the connections . the old one had 3 bare wires in it and had previous repairs that were duct taped (yes duct tape). I was assuming that this was causing my problems. I thoroughly cleaned the plugs on the harness. i did extend the wires that lead to the crank and cam sensors so they could be re-routed away from the head and removed easier.

I replaced the crank sensor [eichlin from NAPA] (the crank was rotated about half a turn removing the harmonic balancer) and the cam sensor (a cheapy from autozone.)

as for the history:
Ive owned the car for a year, have done plugs/wires, fuel pump/tank cleaning, SC oil, middle and rear coil, radiator, and regular maintenance. the car started having intermittent sputtering/stumbling issues back in February after driving for and hour or so.

Im planning on swapping the cam sensor today with my old one to see if maybe the new sensor is bad. next Im planning on putting in a reman PCM. the car did run on sunday night after the battery was unhooked for about 1 hour... started right up and drove fine but it did seem to have a slight miss. monday morning, i went to start it it stumbled and didnt start, i cranked it again and no fire at all. i unhooked the batt again but no fire... just cranks and cranks.

Im thinking maybe i damaged the PCM when removing the battery cable as it makes intermittent contact with the battery as i remove/install the bolt on the battery cable.

Since the car isnt driving, i havent been able to get to autozone to get the code pulled. Im going to try to do that today if at all possible. the local mechanic that can read it wants $150 to come out... Ill buy an actron 9185 for the same $

Would rotating the crank with the 2 sensors off cause the PCM to lose its reference of the crank position?

thanks a lot for the help albert

jeff

No problem, I'm getting it now.

THere are a couple sellers on eBay for the PCMs, I think your P/n is 16183247, and the "delco authorized" seller wants $214 for one. If you search using the P/N you most likely will find them for much less, good-used-pulls. I am thinking $50 - $100.

I can not think of any reason other than a PCM malfunction to cause the TC to run at start-up.

And I am not sure that rotating the crank with car/sensors off can confuse the PCM, a CASE learn will not hurt though. I don't think the Actron does that, the OTC Genisys I think does. A lot of the 'chains' and larger independent garages can do that, not just the dealer.

I am guessing the PO or a mechanic the PO hired was messing with the ICM wiring, most likely because the crank sensor was failing and the mech coud not find a code (when they go bad they don't set a code) so he/she ws looking for an ignition problem that did not really exist. The kind of problem you describe has, for me, been the crank sensor or ignition switch and that's it. I am on my 3rd crank sensor and 2nd ignition switch.

About that cam sensor it would not be the first time a cheapie sensor was bad new. I'd say that is probly not the issue, car won't run at all w/o crank sensor, my understanding is car will be tough to start and run poorly if cam sensor is malfunctioning.

About the PCM damage more likely it was wiring shorts in the ICM harness that run to the PCM, I'd think. I doubt it was hooking up/taking off the battery. And after all this I wonder if something may be amiss with your ICM.

Albertj

ya its a mystery to me.

Well I put the old cam sensor back on and no luck... they had different ohm readings between the 3 pins. the new one read resistance between all the pins, the old one read resistance between one pin and the center and no resistance between the other outer pin and the center and no ohms between the 2 outer pins.

I unplugged the battery for about 5 minutes and the trac motor came on and cycled very quickly about 3 times. weird.

I begged autozone to let me borrow their actron and they said they will so Im gonna grab the codes tonight and go from there.

I wonder if the crank sensor from NAPA is bad... Ill have to check it tonight too if the codes dont tell me anything. Im also going to check the main harness firewall plug and make sure its alright.

Im wondering how the PCM knows where TDC is... the balancer didnt seem to have any "special notch" for that... I didnt really look that closely at it though. Be my luck that i get a bad NAPA part.

the thing to remember is... the car ALWAYS started right up...always. it may have had issues while running but it always kicked on. thats what has really got me frustrated.

Ill get those codes and report back

thank you very much albert.

Jeff

BTW, sunday i did pull a plug wire and had no spark at all.

The balancer doesn't need to know where TDC is. As long as the timing chain does, your ok. A bad crank sensor will cause no spark, as the PCM can't know where TDC is without the crank signal. The reluctor wheel that the crank sensor reads has notches in it, some with different spacing and width. That's how the PCM knows where TDC is.....

Remember when I said in my first reply to this about a bad driver within the PCM? If the same codes came back, I'm thinkin your PCM is fuct, or that plug you mention. The chances of you getting 2 bad Crank Sensors is nil, but possible.

That code you had about the IC circuit (P0341?). That's 1 of 3 things (as I stated before)...the PCM, the ICM, or a bad wire. As I read, I think (we) all suggested that you merely replace the Crank Sensor "while you were in there", as eventually it will go bad and leave you stranded. Nobody said that the Crank Sensor was going to cure your problem.

I think amongst all this, you (we) have lost track of the original problem, which has not yet been cured. Again, wish I was there to help.....

well i got the scanner home and it gave me 0626 VATS failure - so its the security system. Someone mentioned this in this thread. the security light blinks as normal but when i turn the key it goes away like it always does.

gotcha on the crank sensor abbadon

I tried cycling the door locks with my remote 3 times (with the key off and on) and nothing.

So I guess this would cause the engine to not give spark then right??

Im not sure what to do with this.

What needs to get replaced?

thanks for the help guys... looks like were getting somewhere now.

jeffyd123 wrote:

So I guess this would cause the engine to not give spark then right??

No. The security system disables the fuel injectors. That's why people with security issues mostly have a start then stall concern.....

ya i read that. I posted the wrong code in my previous post... it was a 0626 VATS failure. I corrected it in my post.

I am trying the thing to leave the key on for 11 minutes ... see if that works

well the trick of leaving the key on for 11 minutes didnt work.

I cleared the code from the car but the CEL is still on. the scanner shows no codes

any ideas?

thanks

Well Jeff, let's go back a few.....you said earlier you had no spark. You need to find that problem. Go back to page 1 of this topic and look at the schematics of the ICM. You need to check for Ignition voltage at the ICM (Pink Wire). If you have voltage (KOEO), you know the Ignition Switch is supplying power.

Do me a favor. Follow this flow chart and see what you come up with.
I know the first few boxes of this chart says to diagnose other codes first, but we do have a suspect PCM, or still possibly wiring, so just try it. It's a fairly simple check with a DVOM and a Test Light. Again, use the schematics on Page 1.

ok will do abaddon. thanks

got a question... would the PCM possibly be damaged if the CEL is on and there are no codes (i cleared them with the scanner and none show up?

Now the SES light is on with no codes? That's odd. It's not the first time I've seen (heard of) it. That light is directly connected to the PCM yes, and it is possible. Myself, personally, from what all has been posted, am thinking your PCM is trash. We need to make sure all wires and/or components are ok first. The above flow chart will help you determine why you have no spark (ICM or PCM), as well as checking that pink wire from Page 1 (Ignition Voltage). If you can, copy that schematic (the first one) and print it out so you have it to look at while you're testing.

I would post the flow chart for testing the CKP sensor for you, but it requires a diagnostic tool to see if the PCM is getting the proper signal from it....I don't think this is your problem. I would still leave the new one in there for now.

Take your time, and follow the steps in order. Double and triple check if you have to. I would skip to step 2, as we know that other codes are or have been set already. It may be a little confusing to read. If you need help, let me know and I'll break it down to terminals and wire colors for you.

OK will do abaddon...

Question - Can I check the CKP on the car with a VOM?

Im taking the ICM to autozone tomorrow and I have a rebuilt PCM (the same one at NAPA BTW)

They are going to test the ICM on their tester (he verified it would read my ICM). Ill determine if the ICM is bad and take the PCM home and run the flowchart above. I will bring in the old CKP to see if they can test it.
I am also going to put the new cam sensor back on the motor.


Im going to re-check the main engine harness (which I have checked before but Im going to look for those voltages), then Ill try the new PCM if needed.

QUESTION? - Do I need to swap a chip in the PCM?

The SES being on with no codes worries me too...


thanks buuuuuuuuddy

jeffyd123 wrote:

Question - Can I check the CKP on the car with a VOM?

You can, but access to the wires isn't easy. You can however use the ICM harness to check for the CKP signal. Look carefully at the first schematic from Page 1. Follow the CKP wires. Look at Sync Signal, Crank Signal, Sensor Ground, and Sensor Feed. All 4 of those pins on the ICM go to the CKP. You can backprobe (carefully without piercing wires) those terminals at the ICM (with it plugged in) to see if the ICM is receiving a crank signal. You can also check the sensor ground and what not. Examine that schematic and use ur noggin. If you need more detail, lemme know.....it sounds like you can figure it out. I would worry about Crank Signal And Sensor Ground.....set the DVOM to AC, turn the engine over, and make sure a "signal" is present. Check Sensor Ground from that terminal to chassis ground, you should have continuity.

jeffyd123 wrote:

QUESTION? - Do I need to swap a chip in the PCM?

Yes, there is a PROM that needs to be transferred to the new PCM.

k will do thanks.

this should be interesting... if the CKP isnt working the PCM should throw a code... I would think that would be a strong indicator that the PCM is toast.

I got to fix my car! Im driving a FRIGGIN MINIVAN for work and it sucks! I have to go around corners at 15 MPH! LOL

thanks again

jeffyd123 wrote:

this should be interesting... if the CKP isnt working the PCM should throw a code... I would think that would be a strong indicator that the PCM is toast.

See, this is where it gets interesting. Most fault codes will not set until the PCM detects a problem after 2 Ignition Cycles or Drive Cycles (trips). When the CKP goes bad, it's almost like the PCM doesn't know the car is turning over, and the ICM has no signal to produce spark with, and therefore can't send a sync signal to the PCM (which still thinks it's not turning over). Get me? It's a stupid cycle that repeats itself over and over. In a nutshell, the vehicle must be running to throw that code. Also, the CKP signal runs through the ICM, so which code should it throw? I bet Eldo has some more input, he's better at explaining this stuff.

I honestly think it's a programming error. They put too much demand on the CKP sensor. On newer cars, when the CKP goes bad, you can crank the car for like 20secs. After the PCM sees no CKP signal, it will read the CMP sensor to determine TDC, and begin to spark. The car will then run, but no Spark Advance or Retard will happen. The PCM runs in a "base" mode. Then and only then the PCM can throw a code for the CKP. Unfortunately, our Rivs were born in the "dark ages" of that technology.

Thanks, but actually that's the best explanation I've seen as to why the Crank sensor hardly ever throws a code.

Personally, I think this is a case of the humans overlooking something, rather than a technical limitation. I posted in the Dislikes thread how inane it is that the car is smart enough to sound a chime if you leave your turn signal on for .7 miles, yet still allow you to grind the starter when the engine is running! Obviously, with a tach signal and a security-system starter-interrupt, all the parts are there to prevent this, they just didn't think to program it in.

With the CKP sensor issue, it seems to me that they could make the engine at least run in 'limp-home' mode with only a cam signal... Also, the SII motors have both 3X & 18X crank sensors, so they must have managed to design a fault in the module that takes out both Hall-effect switches at the same time.

Sheesh...

I guess I got very lucky that my car tripped a code and set the CEL ON for about 10 seconds before it went out again.
During this particular incident the car was being driven at about 30 mph around Podunk and instead of dying and coming to a stop, as it had done before, all power was interrupted briefly to the ICM & CKP Sensor I guess for just a split second. To me it just felt like a very harsh shift or something like that at first until I realized what had just happened.
In hindsight it was a complete interruption of ignition power for a split second and when it kicked back on the car kicked, it wasn't smooth , but that was the first time I had gotten a CEL where all previous events the car died and I coasted to the side of the road and restarted with no problem or codes. I had been leaning toward replacing the CKP Sensor anyway, but the light and code was all I needed to know I had one of two possible things happening.
A bad or intermittent wire connection in the CKP circuit or a bad switch that was just beginning to fail.
After checking out the whole wiring harness i replaced the CKP sensor and all has been good so far.

hmmm thats interesting guys.

I took the ICM to autozone and they said its fine... so I bought the new PCM.

Im going to check out my new CKP, recheck the harness for the 9th time and see what happens...

pray for me

Thanks everyone

Jeff

Please tell me you checked (or tried) that stuff.....I don't want to see you have $600 invested and still have a problem.....

Let us pray.....again

Well got an update...
Checked out some of the wires... no luck. I did verify that the pink wire to the ICM is supplying power. I then put in the new PCM and no start... had the SES light on with no codes just like the old PCM did.

checked the 3 plugs to the PCM to see if they have numbers on them for identifying the plug number... they didnt have any so i decided to try and verify if I wasnt getting spark. I made sure that I FIRMLY reinserted the PCM plugs this time.

unplugged #5 and put a screwdriver in it turned car over... it started right up!

Put the wire back on... started right up and runs pretty smooth. I am now assuming that the PCM plug wasn't inserted firmly enough into the PCM.

tried starting it a few times... started right up. no SES light

took it for a drive to put some gas in it (about 2 miles). on the way back I ramp up the gas to about 3/4... engine dies. wont restart. try it for about 4 minutes.

Push on the PCM plugs to see if they are not making good contact... wont start.
checked the fuse center under the back seat. verify that the fuel pump is running by pulling the fuse... plug fuse back it... it starts right up.

drive it home (1/4 mile)

scanner gave me these codes:
P0321 - - Ignition System Problem, 18X Interrupts Lost Signal
P0261 - - Ignition System Problem, Electric Spark Timing, EST Not Toggling
P-626 - VATS error (the key wasnt all the way in so Im disregarding this for now)
P0670 - - Quad Driver Module, QDM 4 Fault (Im disregarding again due to the AC clutch being activated by a switch in the dash) but maybe its a bad ground.

Im going to test the ICM-to-PCM wiring tomorrow .

Maybe the new CKP is bad after all (today I was assuming it wasnt). I cant get at any wiring at the ICM plug while its plugged in to test the CKP like you told me abaddon. I would have to pierce the wires which I would rather not do.

I'll report back if I find anything