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Discussion Starter · #1 ·
ASR Engaged last night and caused car to stall. Finally started up and stalled a few more times. Today wont start. No check engine light came on like when the opti gets wet but it feels to me the opti went. Any suggestions please.
 

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Not a traction control expert, but I do know it works by selectively applying the rear brakes of the car to prevent wheel spin.

If your engine is stalling while in neutral or park, then I would look elsewhere for the stalling problem. Just because the check engine light didn't come on, doesn't mean you don't have a code present. Dtc 16- opti low resolution pulse missing dtc's 41 & 42 both icm related codes, don't light the check engine light, but can kill the engine when present. There are other soft codes that could be present. Obd2 uses different, and more code numbers, but there are soft codes in obd2 also, as you didn't state year of car.

So get a scanner hooked up and see if there are codes present.
 

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Discussion Starter · #3 ·
It is a 96 z 28. I disconnected the battery hoping it would clear codes and reset the pcm and it did not help. Now that it wont start will a code back that I can retreive?
 

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I'd scan for codes to see if you have any of the silent ones that don't light up the ses.
But codes are funny, sometimes they don't set even with a problem.
If your suspecting the opti, go to the sticky threads of the lt1 engine section and watch the diagnosing the opti video. Do the tests, also check the opti wire harness as it goes bad sometimes.

Do some old fashioned troubleshooting. www.shbox has coil and opti testing. 4th gen section has 96 factory service manual. It has wiring diagrams, troubleshooting charts, pcm connector symptom, component location, and a lot more. Find in regular threads of 4th gen section. Look for thread titled "GM service manuals"

You'll be looking for bad wiring and connectors, blown fuses, bad grounds, etc. Check out the electrical part of ignition switch, located under dash attached to steering column. It provides power to all ignition on fuses. Look for burnt connector pins, wires etc.
 

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Discussion Starter · #5 ·
Hey cocobolo we have been talking via e mail I just wanted to make sure you know I'm the same person. I posted this when I was on the fence about the opti or the pcm. Now I'm leaning towards the pcm. But still very confused and frustrated.
 

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Discussion Starter · #6 ·
So when the ASR engaged pushing the gas pedal up I pushed through it hoping to avoid traffic when it stalled. However it did start back up in ten minutes but when I hit the pedal a lil hard it did nothing. Softly pushing the pedal got me home but did stall 3 more times. Now will not start at all. Hope that is more insight.
 

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While it is possible for the pcm to fail, it doesn't happen very often. Many a pcm has been changed, only to find the problem still is there. However, I do recommend having a spare pcm, that's in good working order, just so you can swap it out when you think you have covered all the bases and want to give it a try.

Your greatest tool in finding a fault that is elusive is knowledge of the systems on your car and how they interact with each other. As an example, a loose ground wire, or one corroded, etc can cause all sorts of symptoms. Especially if it's a pcm ground.
Your car is 17 years old now, it has a ton of wiring, connectors, splices, connector pins, etc, all of which can cause driveability problems, no start problems, etc.

I still suggest the 96 service manual. Find the pcm symptoms chart. Check each pcm connector wire that says a no start condition will occur if there's a fault. There's a bunch of them.

Study the wiring diagrams, look for any wiring and connectors that aren't good.
 

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Let us know what you find. Don't know if the 96 has a reluctor ring or not, but when my timing jumped a tooth at a stop light, it would not start back up. However, it could have been my opti as well, because when I removed it plfound hard to turn by hand. Got fuel pressure? Constant 55-60psi?. Got spark?
 

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i'll tell you a bit about the system since i've worked with them a bit

your ASR system on your 96+ car is controlled entirely by the body control module, not the ecm. the ecm does play a part, but only by getting timing retard signals from the BCM.

if the ECM had failed somehow or the traction control retard wire to the ecm was broken, traction control would still work, although stage one would be considered a fail and it would immediately go into stage two and three (see below). i have unhooked the timing retard wire. ASR still works fine, it's just more aggressive.

it has a four channel wheel speed reluctor system by default, for 96, i think... a reluctor on each wheel. crap on the reluctors or a failing sensor can cause these issues. they are magnetic sensors, metal will stick to them and probably screw stuff up.

it's worth trying to clean them before going any further. they are the same reluctors used for ABS. the ABS and ASR system on your car are fairly integrated.

when rear wheel speed is higher than front (according to the reluctors), it assumes you're doing a burnout.

ASR on the 96-97 cars is a three stage system, different from the ones that just apply brakes.

stage one, timing is retarded. the body control module sends a traction control timing retard signal to the ECM. this is the same signal as the old TCS system used. it retards a certain amount of timing, based on a table in the ECM relating to vehicle speed and rpm i think. at this point the LOW TRAC light doesn't go on, as it's considered just a mild correction.

stage two applies the rear brakes using a solenoid on the ABS module. it only produces a little bit of braking force. the LOW TRAC light should flicker at this point or just stay on, i forget which..

stage three uses the motor and throttle cable thing on top of your drivers side valve cover to force the throttle closed. the LOW TRAC light goes on at this point, and remains on for a few seconds even after traction is restored.

if any problem is detected with ABS or the speed reluctors, the ABS and ASR systems are both disabled for safety, but error checking is primitive and never ends up working. pulling your ABS fuses (ABS IGN and ABS BAT under your hood) disables ASR and ABS at the same time.

if you're having issues with it, do that until they're corrected, as it could easily cause you to get rear ended or lose control in a maneuver. you might end up wanting to just leave them unplugged as both of those systems are for pussies and soccer moms.
 

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Discussion Starter · #10 ·
Scanned it today with actron cp9180 and no codes. Actually got it started tonight warmed up took it out to the street hit the gas and stall. Back in the garage still no codes. Weird man weird!
 

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Steveo, thanks for your explanation of the 3 stage traction control. Now, since surfdaddy is having a stall out problem, do you think ASR has anything to do with that. My instincts say no, but since you are up to speed on the system, what do you think.

I'm leaning in the 2 separate problems at the same time category. Ist problem is ASR, and car has 2nd problem with fuel, ignition, or sensors. This is the problem that is causing the stalling.
 

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Discussion Starter · #12 ·
Hey guys thanks for all your insight. Tomorrow I was going to call and or take it to pep boys they bring out a pretty nice scanner. Do you think theirs will detect any codes that the actron did not or will it need to be brought in and diagnoised by a bigger scanner/whatever they hook it up to?
 

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Discussion Starter · #13 ·
Took it to firestone to be diagnosed they came up with MAF replced it with a aftermarket and it ran better but light came on and I had codes took it back to them and they said to get an OEM scensor got it home and the MAF unplugged. Put the OEM in and no start unplug it and start put the other one back in and no start unplug and it starts.
 
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