348 Spyder and red Stop Lights

Check the bulb. Make sure it isn't burned out or that it hasn't been removed.

 

You mean the slow down lights that are on the vertical edge of the panel? They are driven by the cat ECUs, and will not light if they are disconnected. Check these, specifically connections to the ECUs themselves. Odd that both would go out, though. Did you major include a new exhaust without cats?

Or like Ernie said, bulbs.

 

picture would help

 

If slow down lights come on and you ignore them the manual says it will shut engine down. Is that correct

 

My SDL 1-4 turns on intermittently, it corrects itself. The harder I drive my the less the light turns on.

 

I'm confused by your location, name, and color of the lights. Slow Down are typically red, and CEL are Yellow, at least in all the cars I've seen. Let's see if we can clear this up:

Lights 1 and 17 in the diagram are your Slow Down lights. These are connected to the catalytic converter ECUs on both sides of your engine. They will light momentarily when they key is turned on, and will light if they determine that a cat is reaching a high temperature.

There is also a second, higher threshold at which point the cat ecu(s) will send a signal to your main ECU that will shut down the bank. I *BELIEVE* that the light will flash when this occurs, but I may be remembering incorrectly.

So yes, they can shut down a bank. They are also notoriously prone to failure. Failure often manifests as lights coming on when cat temps are normal, and based on anecdotal stories, the cat ecu sending the "shut down" signal to the main ECU with or without the light lit, and without sensing a high temperature.

These are critical safety devices if you have cats installed, as cats with aging elements can clog and get hot enough to start an engine fire at worst, and damage your engine at best. You can get cat ECU replacements, or you can repair your existing ones. Fchat has info on both approaches if you search. Ignoring this issue is not recommended.

If you don't have cats, you can safely remove these by simply unplugging both ends of the cat ecu and sealing them temporarily (to prevent corrosion in the connector). Please don't cut the lines or permanently remove them so that any future owners who may require cats for their state can easily restore the system if needed.

Both of these lights are red, at least on every car I've seen.

The Check Engine Lights are 5 and 12 in the diagram, and they are yellow. These should also illuminate when you turn the key on.

Missing bulbs, or removed bulbs for any of the lights mentioned above, has been reported. Lights may be removed to hide an issue by a previous owner or seller, so if you don't see these lights, make sure to replace them.

A 348 will often appear to be fine and show no obvious signs of a problem if a CEL is lit. However, a properly running car will not light the CEL, and if you are seeing one lit, you have a problem and ignoring it will often lead to bigger ones. Don't ignore it.

Very possible that some cars had alternate colors, so hopefully others will chime in if that's the case.

Hope that helps!
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Interesting addition to the above. The CEL lights are in the pod for 1989 models but not used as per the owners manual. I removed my pod to check to see of bulbs were there and they were but never come on when you turn the key to the first position before starting so the manual is correct.

 

Just a guess, but it is likely due to the different ECUs. 89 uses the 2.5 Motronics, while later used the 2.7s.