Loose PL connector

[UncleDave]

Sine the other thread went off on a tangent, I decided to stary a new one. Background it toward the end of the thread here: http://www.turbobuick.com/forums/general-turbo-buick-tech/329289-new-build-how-many-miles-before-getting.html

So, I pulled the ECM and discovered that my PL had come halfway off the edge connector! It's not as tight a connection as I would have hoped to begin with. Haven't put it baqck in or started the car yet (people in house still sleeping, lol), but my question is this: could a loose PL edge connector cause mayhem with the ECM and drivability issues?

 

[RmvBfrFlght]

could a loose PL edge connector cause mayhem with the ECM and drivability issues?

Yes. That edge card connector is an extension of the ECMs address and data bus along with other signals. Any disruption to the signal integrity will cause the ECM to malfunction. Code 42 is common in this case. As it is a sensitive test within the ECM.

I was going to post this in your other thread, then saw this one. Don't drive the car with an active code 42. Pull over as soon as possible and key-off for at least 10 seconds. Then restart the engine.

The reason is that an active code 42 locks the ignition module in bypass mode. It will spark the plugs at base timing (10* BTDC). Which causes overheating of various components.

Note that this is not when there is a stored code 42, just when a code 42 is actively set during this run time.

RemoveBeforeFlight

 

[UncleDave]

Thanks RBF, I hope this is it. Still a host of other issues, but I hope this fixes the Code 42.

~Dave

 

[TurboBuRick]

Mine comes loose too. The contact points on the ecm are long and go all the way to the edge so even if it slides down a little it should still retain it's connection.

I have seen where internal problems with the pl have causes drive ability issues.
If you think the pl might be reaping havoc, remove it from the ecm and see if it changes anything.

 

[84BuickGNYorkPA]

I used 2 face tape, stacked up, 2 layers thick to hold the PL board to the ECM, also opened up the vent slot in the kick panel because the usb cord would pull the board down. Between the two corrective actions, have not had any more problems.

Chuck

 

[UncleDave]

...also opened up the vent slot in the kick panel because the usb cord would pull the board down...
Chuck

That's exactly what I did, had the same issue with the USB connector. Glad it's not just me.

 

[Jerryl]

Yes. That edge card connector is an extension of the ECMs address and data bus along with other signals. Any disruption to the signal integrity will cause the ECM to malfunction. Code 42 is common in this case. As it is a sensitive test within the ECM.

I was going to post this in your other thread, then saw this one. Don't drive the car with an active code 42. Pull over as soon as possible and key-off for at least 10 seconds. Then restart the engine.

The reason is that an active code 42 locks the ignition module in bypass mode. It will spark the plugs at base timing (10* BTDC). Which causes overheating of various components.

Note that this is not when there is a stored code 42, just when a code 42 is actively set during this run time.

RemoveBeforeFlight

That is some GREAT info!
I am continually amazed how much you know about these cars!

Question: Can this cause ECM failure?

 

[RmvBfrFlght]

Question: Can this cause ECM failure?

That the PL connector walking off the ECM edge card connector causing the ECM to fry? Possibly. But it isn't something I'd worry about.

RemoveBeforeFlight

 

[UncleDave]

OK... Still getting code42. Using a known good module & coil pack, no problem found with the wiring, good grounds. What are the chances that either the ECM, chip(TT), or calpack are bad?? Could one of these also contribute to an extremely rich startup and/or idle?

 

[TurboBob]

There have been no instances of a PL damaging an ECM.

There have been a few instances of 'issues' causing the PL or the ECM to fail, but those were due to external failures.

The ECM is over sensitive to code 42 in my opinion, and many things can cause it. Back in the days of Direct Scan, a long ribbon cable could cause it. This is one reason the PL was designed to mount inside the ECM.

Code 42 can be caused by a bad chip (rare, but it happens), a loose chip socket, a bad ECM, a bad ignition module, wiring, or module plug (increasingly common due to age).

If you remove the PL and the code 42 no longer occurs it points to noise being picked up by the PL. THis noise could be due to flaky plug wires or corroded coil terminals causing noise that is picked up by either the USB cable, laptop, or analog cable, or analog grounding.

We should go thru some of these step by step to nail this down.

Bob

 

[TurboBob]

is the code 42 an every time thing, or intermittent?

Bob

 

[UncleDave]

Hi TurboBob,

Electrical issues are always the most frustrating to resolve!

Code 42 is intermittent. It comes on after driving the car for a while, but the length of time before appearing varies widely. It could be within a minute, or within 20 minutes, but it always appears eventually.

It used to be that the car would run fine before the Code 42 appeared, now it runs rough all the time. I checked for vacuum leaks, loose intake/plenum bolts, loose ground connections, breaks in the wires, etc. I have replaced the module with a known good module. I have replaced the coil with a known good coil. I have wiggled various portions of the harness while the engine was running and the code would not set; I have to actually drive for it to appear.

Come to think of it, if I do not use the brakes, the code will never appear; it could idle for a half hour with no codes even though it idles like crap. After it idles for a few minutes and is warmed up, when I press the brake pedal, the SES flashes briefly and the engine will stumble. After the Code 42 is set, when I press the brake, the SES will either turn off, or it will remain lit but the engine will not stumble. What could be the correlation between the brake pedal and the SES light/code 42?? I keep rechecking my grounds, I'm at a loss here. Can I run a jumper to ground temporarily just to be absolutely certain I have a good ground connection, in case there is a break internally?

I have a TT chip, I really couldn't say whether it's bad or not. The chip socket does not seem loose at all. Checking the wiring on the BYPASS and EST leads has not shown any issues there.

How sensitive is it to the condition of the module connector? Mine looks quite 'seasoned'... Can a corroded connector cause problems that would only generate errors once warmed up?

First thing I'm going to do is remove the PL completely and see what happens. I doubt that's the issue but it's the simplest thing to try first.

 

[TurboBob]

Hi TurboBob,

Electrical issues are always the most frustrating to resolve!

Code 42 is intermittent. It comes on after driving the car for a while, but the length of time before appearing varies widely. It could be within a minute, or within 20 minutes, but it always appears eventually.

It used to be that the car would run fine before the Code 42 appeared, now it runs rough all the time. I checked for vacuum leaks, loose intake/plenum bolts, loose ground connections, breaks in the wires, etc. I have replaced the module with a known good module. I have replaced the coil with a known good coil. I have wiggled various portions of the harness while the engine was running and the code would not set; I have to actually drive for it to appear.

Come to think of it, if I do not use the brakes, the code will never appear; it could idle for a half hour with no codes even though it idles like crap. After it idles for a few minutes and is warmed up, when I press the brake pedal, the SES flashes briefly and the engine will stumble. After the Code 42 is set, when I press the brake, the SES will either turn off, or it will remain lit but the engine will not stumble. What could be the correlation between the brake pedal and the SES light/code 42?? I keep rechecking my grounds, I'm at a loss here. Can I run a jumper to ground temporarily just to be absolutely certain I have a good ground connection, in case there is a break internally?

I have a TT chip, I really couldn't say whether it's bad or not. The chip socket does not seem loose at all. Checking the wiring on the BYPASS and EST leads has not shown any issues there.

How sensitive is it to the condition of the module connector? Mine looks quite 'seasoned'... Can a corroded connector cause problems that would only generate errors once warmed up?

First thing I'm going to do is remove the PL completely and see what happens. I doubt that's the issue but it's the simplest thing to try first.

sounds like grounds. The powermaster motor kicks on when you hit the brakes, and its grounded to the firewall.

B

 

[UncleDave]

I don't have a Powermaster, it's an '84 -to-'87 conversion with Hydroboost.

There was a separate black ground lead on the '87 harness when I did the conversion, I attached it to the firewall. If this is supposed to be the Powermaster ground, and I don't have a Powermaster, would this cause issues? Should I just leave it disconnected? I didn't have a donor car to refer to when doing this...

 

[Jerryl]

That the PL connector walking off the ECM edge card connector causing the ECM to fry? Possibly. But it isn't something I'd worry about.

RemoveBeforeFlight

There have been no instances of a PL damaging an ECM.

There have been a few instances of 'issues' causing the PL or the ECM to fail, but those were due to external failures.

The ECM is over sensitive to code 42 in my opinion, and many things can cause it. Back in the days of Direct Scan, a long ribbon cable could cause it. This is one reason the PL was designed to mount inside the ECM.

Code 42 can be caused by a bad chip (rare, but it happens), a loose chip socket, a bad ECM, a bad ignition module, wiring, or module plug (increasingly common due to age).

If you remove the PL and the code 42 no longer occurs it points to noise being picked up by the PL. THis noise could be due to flaky plug wires or corroded coil terminals causing noise that is picked up by either the USB cable, laptop, or analog cable, or analog grounding.

We should go thru some of these step by step to nail this down.

Bob

Thanks for the info.

Just helped with a PL install on a friends car a few weeks ago, no other changes.
Car ran GREAT before install.

Immediately after the install, code 42 appeared. Cleared the memory and it came back, right at start-up.
The car would load up as if it was running in limp mode.

Checked pins, grounds, swapped chips, etc.

After some diagnosis, we swapped the ECM and the car is back to running perfect.
So, I am thinking something with the code 42 resulted in overheating and fried the ECM?

 

[UncleDave]

Interesting, Jerry. I'l be trying a different ECM also, without the PL at first, just to rule it out. We'll see what happens.

 

[UncleDave]

Borrowed a known good ECM today. I put the TT chip in and went for a short test drive... So far, so good. Granted it was a short drive, but previously the SES would light halfway around the block or as soon as I stepped on the brakes. With the 'new' ECM, after idling for 5 - 10 minutes and driving about 5 miles, no SES. I'm keeping my fingers crossed that this is it!

 

[luisturbog]

Borrowed a known good ECM today. I put the TT chip in and went for a short test drive... So far, so good. Granted it was a short drive, but previously the SES would light halfway around the block or as soon as I stepped on the brakes. With the 'new' ECM, after idling for 5 - 10 minutes and driving about 5 miles, no SES. I'm keeping my fingers crossed that this is it!

sorry for waking up an old thread but I'm having the exact same issues now. Did you ever solve this problem?