Intermittent Tachometer issue
 

I'm new to this forum, so if this is posted in the wrong place can you please move it?

I have a beautiful '97 SLS that just recently began to die occasionally while coming to a stop. It seems to happen within a few blocks after a cold start. Once it is warmed up, it has never happened. Checked the fuel filter and it is not clogged. Didn't do a pressure check at the fuel rail, but the fuel pump builds pressure quickly and seems to hold fine. This has happened about half a dozen times over the past few days. :mad:

At about the same time the tach began to occasionally go dead. Today I cleared all the codes and was performing a GM OBDII Driving Cycle to run the diagnostics on the vehicle (I'm really not experienced -- this site has great info!). During this test run of about 15 miles the tach was completely dead the entire time. I turned the engine off and then checked for codes (found none), and when I started the engine again to drive back home the tach worked fine.:confused:

I'd sure appreciate any help anyone can offer here. I've gotten much information from this forum in the past and have a high regard for you all.

Thanks in advance for anything you can offer me.

OK today started with the codes all cleared. On leaving the house with a cold engine (southern arizona, so it isn't frigid) it stalled within 1 mile at a stop sign. When I began to go again under light acceleration it almost immediately surged, and the check engine light came on. I immediately checked for codes, and found P1350 (Ignition control system), P1375 (EC 24X Reference circuit high voltage), B1910 (Gen L-terminal open circuit) and B1971 (inadvertent power) in the current codes.

As I was driving I cleared all the codes (dumb!! kinda like texting while driving!) and the check engine light went out. And then a split second later it came back on and AT THE SAME INSTANT the tach went dead. I checked again (while driving) and again had P1350 (Ignition control system) and B1910 (Gen L-terminal open circuit).

After driving for an hour to my destination I checked again and it remained only those two. Other than the tach remaining dead, everything else was fine. :confused:

Any ideas? I'm putting injector cleaner in to hopefully solve the cold stalling issue...

issue solved
 

Fixed the issue today. For code p1375 the GM manual said to check the resistance at the plug up by the ICM to see if they are in range. One crank position sensor was ok, the other was not. Next it said to check the resistance at the sensor itself. Still no good.

Replaced the crank position sensor, and all the issues cleared up. At least for now... :cool:

This GM manual has saved me the cost of it many multiple times so far. I'd highly recommend getting the 2-volume set (it is specific to MY model, MY year) for anyone who is doing their own work.