'95 SC Riviera Intermittent Stalling & Flashing PRND321

Hi all ... been lurking these forums for a while and picked up a lot of good tips and tricks, but I've got an issue now that I can't find symptoms for anywhere ...

Recently, my 1995 SC Riv has been stalling intermittently while idling, and will sometimes not immediately restart, as if it's being starved for fuel it seems.

Also, I've noticed the PRND321 indicator flash all its lights on and off occasionally while driving, and occasionally when turning the key to start the car before it is started (could this be a hint toward something? I've found no posts regarding the flashing PRND321). I don't get a steady SES light, it will pop on maybe 1/8 times that it stalls -- I've also noticed my Temp/Fuel gauges drop and reset while the PRND321 indicator was flashing once or twice... I can't do anything to replicate the stalling either -- it seems it just happens when it feels like it.

Under load, it will operate fine, it's usually stopping at lights or stop signs that I get paranoid that I'm going to stall.

No major mods have been done to the car, just stock & routine maintenance, and I've been using 93 octane for the last 30k+ miles. Car was tuned up within the last 30k as well -- I've got about 146500 miles on it now -- recently (within the last year), the SC was replaced with an OEM rebuild, the EGR valve was replaced, fuel filter (<3000 miles ago), and a few Techron fuel system treatments have been done with no helpful result... The car ran like a million bucks after those repairs were made, and this just arbitrarily began to happen.

My initial thoughts as to what could be wrong are fuel pump (however, I think I would notice a problem at all speeds, not just idle), Dirty/Fouled Fuel Injector(s?) or potentially a faulty PCM?

I just wanted a few general ideas before I start throwing (expensive) parts at the car ... Thanks for taking the time to read my long winded post ... any and all thoughts are appreciated!!

How do the plugs, fuel filter, and air filter look? These are all things I'd replace if they haven't been in a while. Also take the MAF sensor out and clean it with electronic parts spray. How old are your plug wires?

AA wrote:

How do the plugs, fuel filter, and air filter look? These are all things I'd replace if they haven't been in a while. Also take the MAF sensor out and clean it with electronic parts spray. How old are your plug wires?

Fuel filter was just replaced, plugs and wires were replaced somewhere around 30k ago, wires look healthy, although I haven't pulled a plug out to check them. The air filter is in OK condition, not poor but not brand new. Also, the MAF sensor was cleaned when the SC was replaced, however I guess it could be cleaned again easily enough.

Check the ignition related wiring. Ignition control module to PCM, Ignition control module to cam sensor/crank sensor. If you find something questionable, but you're not sure, pull back some insulation on both ends of the wire (close to the connectors) and clip a temporary bridge wire to it. If that eliminates the problem, then replace the wire with a new one. If not, just unclip and cover the opening back up.

I've had that same symptom in my 97. My MIL didn't flash like yours sometimes does but we are talking about two completely different PCMs. My problem was with more than one wire and one was very high resistance which the computer may see as open or an impossible value. The other one was a fluctuation between open and shorted. That's what caused the intermittent dieing.

Good luck!

I should make a point that to check these wires, you will certainly
need a wiring diagram. Mine is for a 97 so that won't help you but
Autozone.com might have something to get you going or if you have access to Alldata, that would work.

my money is on a faulty crank position sensor. especialy with that many miles, CKP is a know problem on the 3800's.

Thanks for the pointers turtle and Mr.Riv -- I'll check out the connections in the daylight.

A faulty CKP would cause the car to just arbitrarily die? Interesting ... The work to replace it doesn't seem much and its an inexpensive enough part to replace I think ... However I was reading the OdDemand instructions for replacing the sensor and it said I would require a Balancer Remover to remove the harmonic balancer -- Will normal shop tools suffice or will I need the actual removal tool to get the job done?

You'll have to have a puller to remover the balancer. If you have 30k on the plug wires,...I'd change the plugs and wires first. You can't really tell if the wires are always bad just by looking at them.

Just tried to start it a few minutes ago -- Cranking, fuel pump seems to be running, however I couldn't turn it over -- Now not only was the PRND321 light flashing, but my Temperature display (on the heater unit) began to flash as well ... I think I've got a ghost in the car LOL

It also threw the SES light on while I was cranking -- I don't have a scantool, but since the 95 is an OBD "1.5" type unit, is it possible to read engine codes via the ALDL SES Light Flash method? I've also looked into building a serial cable for connection to a laptop, but couldn't find anything that led to the right design for the '95 OBD I computer but OBD II connector ...

First thing to do is eliminate anything from the possible list of suspects. Check the fuel pressure after the pump has been running for a while. Same type of time as when it would stall.

I've seen a flashing prndl... However it happened when the car was running and did what I called a hiccup. Scanning and lots of beating on the car (beat it when they act up..lol) brought me to the crankshaft position sensor.

In the scans if I watched the run time counter, what happened was it saw a stall and automatically the engine kept running. The counter reset. PRNDL was flashing if it thinks it sees a restart in gear. Keep in mind this is on a 97 B'ville...but GM logic applies to almost all of the line up.

This sounds like it could be an intermittent ignition switch. The symptoms are similar to what I had. I'll try to look at the wiring diagram this weekend and give you a better answer. I haven't fixed mine yet because the switch is $150. If it doesn't start, I just tilt the steering wheel up and down hard a couple of times and it starts every time.

Welcome Steve, and thanks for the info.

Aaron265358

I had the car code scanned today, it threw 3 codes --

P1573 Traction Cntrl Fault Loss of ABS/TCS Serial Data

P0341 Cam/Crank Error

and another code I didn't write down for "Battery Voltage Out of Range"
(I'm assuming this is because I recently disconnected the battery?)


The ABS indicator has been on steadily for a while, and it used to flicker on or off for a little while before it came steady, which says a loose connection somewhere to me I feel ... however, my Traction Control button has never worked (at least the light on the dash has never illuminated when I hit it).

So it's looking like the diagnosis of the Crank Position Sensor was pretty accurate! The mechanic said its possible that the harmonic balancer may be out of spec due to the outer belt breaking a while ago, but my money's with you guys on the CKP...

Also, he mentioned something about a Transmission Lock Sensor? that he remembered being a problem with certain GM vehicles which gave him some of the same symptoms that I'm experiencing.

Could the P0341 error be causing the P1573 or vice versa? Also, what type of scanner will I need to use if I were to scan myself? An OBDII or OBDI? I only ask because I've read many stories about the '95 being the "Hybrid OBD1.5" type system with the new connector but the old onboard diag computer... The scanner the mechanic used was a SnapOn MT2500.

A stall/start from the CKP is one that will toss oddball codes at you.

I got many strange things and was trying to link them when the crank pos code finally set once. At this point, I'd feel comfy with swapping out that sensor as a possible fix.

The tough part is with it being semi intermittent, that makes it harder. If the crank sensor gave up, it could be quickly diagnosed, if it were an electrical short..that could be located and fixed. Intermittents are a pain because you can't duplicate it readily.

this still doesent explain why the PRND321 flashes

Hey Echz I'm from Jersey too, tho I've never heard of Hainesport. If you're looking for a scanner for your 95 there's a post on here that will help. I personally use the actron 9145, available off amazon for about $180. Hope that helps, pm me if you need more info.