PRND321 Flashing

I've searched everywhere and have only come across 1 post, here on rivperformance, in 2008 by echz., the thread went stale with no resolve no update from our member....maybe some fresh owners of the 95 Riviera has or had this problem and knows the exact fix....
PRND321 Flashes with all 7 little selection squares underneath lit up,...at the same time that is going on the ambient temperature flashes and the engine temperature needle dies... it throws a check engine light on and if you come to a stop while this is going on, when you pull away it's like starting off in 3rd gear.....any input thank you

Welcome OBD1.5, A few ppl will chime in hold tight! what i learned is get a scanning tool with obd1.5 features and get the codes that are flashing. My 95 has a obd2 port but a ob1.5 computer i believe( kinda learning myself )any way....Also a factory service manual ,after that the ppl here can guide you in the right direction!

Yes have the scanner as well as the two gm shop manuals for the 95 year g platform....I stumbled on an interesting find here about the black wire on the firewall connector for the cam sensor being one of the codes p0341 and a p0342 the ses light is giving

OBD1.5 wrote:

I've searched everywhere and have only come across 1 post, here on rivperformance, in 2008 by echz., the thread went stale with no resolve no update from our member....maybe some fresh owners of the 95 Riviera has or had this problem and knows the exact fix....
PRND321 Flashes with all 7 little selection squares underneath lit up,...at the same time that is going on the ambient temperature flashes and the engine temperature needle dies... it throws a check engine light on and if you come to a stop while this is going on, when you pull away it's like starting off in 3rd gear.....any input thank you

PRND321 flashing while the shifter is in park (say you never touched it) it means IPC has no data communication with the rest of the car modules. It will also post every single conceivable message on the display plus most of the warning lights will be on. This is common across GM cars of his era, and easily learned about using a general web search.

No this happens while driving usually after 30 minutes it starts flashing then it disappears comes back to normal and while this is all going on I lose my engine coolant gauge, and the temperature gauge outside/cabin flashes too

You're right about the codes it'll light up at least six...I'm zeroing in on the possibility that it's either the v.a.t. resistor on the daily ignition key or the ignition switch itself is vibrating to the border of on/off....I used the spare key today and it didn't happen....no ses light came on...and the rpms stayed very steady....

OBD1.5 wrote:

You're right about the codes it'll light up at least six...I'm zeroing in on the possibility that it's either the v.a.t. resistor on the daily ignition key or the ignition switch itself is vibrating to the border of on/off....I used the spare key today and it didn't happen....no ses light came on...and the rpms stayed very steady....

I vote for the switch, I am on my *third.* I feel the need to tell you that it is difficult to confirm that as a diagnosis. I forget how, some way that you can connect NOID lights to light in a certain pattern if the ign is turned off versus some other failure. I wish I remembered. There is a "gearhead" at my local GM dealer who knows what to do, but it's not in the service manual.

Albertj

Thx Albertj for the input....if I do not get any other possible remedies...I will bump the thread if and when I get a 100% confirmation of what it was.

By the way if it's a VAT key problem the SECURITY light on the dash will indicate that -- that *is* in the service manual and I think in the owners manual with instructions on how to get it to start.  A VAT key problem will not cause the car to quit once started, however.

So much for the VAT key theory.....started flashing as soon as I got to work.....did you change the ignition yourself Albertj?

When I got home, I checked the codes when it threw the ses light on
P0171 fuel trim lean
P0630 battery voltage signal out of range....and for the first time, the battery light also came on.....the good news it isn't stalling on me anymore.

This is what it looks like in between flashing....notice all the bars under the selections...there should only be the one....still trouble shooting the problem

my 95 did the same thing but didn't hurt the performance of the car at all. my mech changed out the Transmission Range Sensor (TRS). This switch is also known as a pressure switch, Park Neutral Position switch (PNP), the gear selection switch, or a PRNDL input switch.np problems since then, Hope this helps some way.

Yes thank you! I am on it....I do not throw parts at it but will read the Rivera "bible" to get info on proper operation and testing procedures