Car died on the way to work

My 94 Caprice has run flawlessly for awhile. Passed E test in the fall, has been getting decent mileage. Today, it let me down. Was on my way to work, going about 50mph. CEL came on. No change in how it ran. After a stop sign about two min later, CEL went off. Two miles down the road, CEL came back. A mile later, I felt the engine cough once. Made it another half mile, and lost power quickly. Engine died, no restart. Coasted into a gas station lot. Car cranks, won't catch. Had it flatbedded home, driving my diesel Jetta.

Immediate thought is fuel pump. I replaced the pump with a brand new Spectra 15 months ago when I did the sender. Figured since I was in there, I might as well. Saved the old pump, just in case. I didn't notice if the pump was priming when I tried to start it, it was noisy in the parking lot.

So, the usual tests, I guess. Listen for prime, 12V to relay, test fuel pressure on cranking. I'll check that CEL code as soon as I'm home. Maybe I can get a pressure tester from the school shop.

Anything come to mind other than fuel pump? Coil/ICM/coil wire?

Fuel pressure gauge is one of the best $45 investments I ever spent. Fuel problems are generally easier to diagnose than ignition problems.

Dang, sure hope it's a simple fix! Keep us in the loop.

The only time I've lost a fuel pump has been when shut off. Car runs fine, turn it off, and then nothing but cranking when trying to re-start (and normally I have just filled up...ha)

Good Luck!

-Mike

Back from work, and from time in the driveway with the laptop. First update: pump is priming. Battery was pretty dead from cranking attempts, put a boost pack on it. Cranks fast, not even a bit of a "catch".

Brought home the fuel pressure tester kit from work. Nice pro set, every adapter possible. I'll check pressure tomorrow.

Freescan reports CODE 42 EST GROUNDED

Off to have supper, back later with research. Feel free to "fix" things while I eat!

found this on a quick search:


GM OBD 1 Trouble Code Information
ODE 42
Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system. During cranking, the timing is controlled by the ignition module and the ECM grounds the EST line. It expects to see no activity on this line at this time. When the ECM enters EST mode, it applies +5 volts to the BYPASS line and expects to see voltage variations on the EST line.
Reasons for the ECM to set Code 42:
? System in BYPASS mode (i.e. EST line supposedly grounded) but activity sensed on EST line
? System in EST mode (i.e. BYPASS line driven with +5 volts) but no activity seen on the EST line

Possible causes include:
1. BYPASS line is open or grounded
2. EST line is open or grounded
3. Poor connections between ignition module and ECM
4. Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise
5. Faulty or incorrect ignition module
6. Faulty ECM

Hi Jay:

If the fuel pressure thing checks out, swap out the coil and ignition module with one from any of the other "B" bodies you have around the place (lost count about a year ago). Check out all the connections and grounds and if that still doesn't work.........here it comes..........It's getting ready......THE OPTI!

With all the water, salt and other crap on the roads in the last few days it could be anything but low voltage wiring would be my first suspect. Might even be the opti harness based on the EST code.

Bill

http://www.nastyz28.com/forum/showthread.php?t=262824

read that,....

Yep, found that one last night while researching. I've also got the trouble shooting chart for the ICM that I'll follow. I've got a spare coil and ICM that I will pull off my spare LT1.

Driving a diesel Jetta is a lot different than a wagon...

I'll post this here for future searches.

Test A (start here)
Clear DTC(s) and crank engine for 15 seconds. Does DTC 42 set? If yes,
go to test B; if no, DTC 42 is intermittent.
Note: DTC 42 will set if voltage on white wire from ignition module to
ECM/PCM is below about 0.5 volt while engine speed is below 3000 rpm,
or the high and low resolution signals from the Optispark are shorted
together. When either of these conditions is present, the ECM/PCM
disables the injectors to avoid flooding.

Test B
With ignition off, disconnect ignition coil module connector, and
connect a voltmeter, set to AC scale, between ICM harness connector
terminal B (white wire) and ground. Crank engine and observe voltage.
Is voltage between 1 and 4 volts? If yes, go to test C; if no, go to
test D.
Note: This check determines if the IC signal from the ECM/PCM is
available at the ignition coil module.

Test C
With ignition off, connect test light between battery positive
terminal and ICM harness connector terminal C (black wire). Is light
on? If yes, go to test E; if no, ICM ground circuit is open (black
wire is broken or not properly connected to ground).
Note: The remaining tests begin to check that the ignition coil module
circuitry is OK. If the ignition coil module loses its voltage source,
secondary voltage will not be produced and a DTC 42 will set.

Test D
With ignition off, disconnect ECM/PCM connector A. Connect test light
between battery positive terminal and ECM/PCM harness terminal A12
(white wire to ICM). Is test light on? If yes, the white wire is
grounded somewhere between the ECM/PCM and the ICM; if no, either the
white wire is broken somewhere between the ECM/PCM and the ICM or the
ECM/PCM is defective.

Test E
With ignition on, connect a test light between ICM harness connector
terminal A (pink/black wire) and ground, and then between terminal D
(white/black) and ground. Is the light on in both cases? If yes, the
ICM or its connector is faulty; if no, the connection from the ICM to
the coil is broken on the circuit/circuits that did not light.
Note: since the ignition coil module gets its power from the coil,
check the ignition feed circuit to the ignition coil for opens.

Small update. Didn't have a lot of time to work on it as the sun was setting, and it was getting cold. However, I did crank it, and it coughed once and backfired. Saw a bit of a black cloud puff out the air cleaner. Started to follow the chart above. Cleared the code. Cranked for about 5 seconds, car started, roughly. CEL came on, car died. Began to check the ICM wiring with my DVOM, and quickly realized that I need two people. I'll get back at on the weekend.

I just verified and the 95 B-carline FSM is almost identical to the F-Carline for DTC 42.  There are minor differences in the schematics, but the text and flowchart are identical.  Namely, we have 451 BLK/WHT (vs 450), #5 (U/H) 10 amp fuse vs #11 and 539 PNK (vs 239 PNK).   Email me if you want the B-car specific schematic.




The 1st few posts from this thread which Nick's link references should be a sticky even though it's for the F-body.

I've got the FSM here. I think it will be ICM. Might be coil. Doubt it's PCM. However, I have spares of all three.

I like the chart I posted, it is the same as the photo, but it actually gives you wire colours instead of "terminal B".

Today was the first day in two weeks that it was above -10C (actually went to a balmy -1), so I went out to work on the car. Took off the old coil/ICM. Sanded all three grounds, coated with dilectric. Installed used coil/ICM, buttoned everything back up. Car runs perfectly.

When you get a code 42, suspect ICM immediately. Easy enough to change on the side of the road, but you'd need your laptop and cable with you to diagnose. I am really starting to appreciate OBD2 scanning on my cell phone.

Back with an update. I've been driving the wagon once every couple of weeks, a TDI Jetta has taken over daily duty. Took the wagon out for a short drive... it died. Exact same symptoms. Code 42 set again. What are the chances that the used pat failed so soon in the exact same way? I'll go through the trouble shooting tree above this time to figure out if it's the ICM (probably) or the coil (less likely, due to the Code 42). I'm out of spares, but I can grab a good ICM off my SS to test if need be.

While we're on topic, why is there a different listing for an ICM for a wagon? Anyone ever notice this before?

ACDELCO Part # D1986A {#10483139} One of our most popular parts
MODULE,ELEK IGN CONT (W/O COIL)

Part Image
CAD$93.13
ACDELCO Part # D1905E {#19106961}
MODULE,IGN COIL STATION WAGON
MODULE,IGN COIL 4 DOORS

If anyone has a couple of spare ICMs, I'm a buyer.

Thoughts/opinions welcomed.

jayoldschool wrote:

Thoughts/opinions welcomed.

coils and icm's both will quit when they get hot,..

will it restart when it cools down?

Nope. Clear code 42, it will return on cranking.