What's the Deal With Those FLOOR TEMP Warning Lights in Malaise Era Datsuns?

Murilee Martin
by Murilee Martin
whats the deal with those floor temp warning lights in malaise era datsuns

A couple of recent Junkyard Find Datsuns (the ’78 510 and ’77 280Z) featured mysterious “FLOOR TEMP” idiot lights on their dashes. Floor temp? Why?

The thing that really put the malaise into the Malaise Era was the inability of the automotive industry to meet US federal and– in the case of cars sold in California— state exhaust-emission regulations without crippling the vehicles (whether this inability was due to Naderite anti-progress bomb-throwers infesting the government or corporate mismanagement and the over-reliance on lobbying to fend off emissions regulations is your subject to debate). While Honda’s CVCC engines managed to beat the tailpipe test without the use of the early, incredibly inefficient catalytic converters, just about everybody else had to bolt a super-restrictive and surface-of-sun-temperature cat onto the exhaust. On low, sporty vehicles that didn’t have a good location for the catalytic converter, an overheating cat could set the car’s interior on fire. Nissan’s solution to this was the FLOOR TEMP indicator light, which used a temperature sensor near the catalytic converter to warn the driver to slow the hell down. We can assume that no Datsun drivers actually read the owner’s manual (as a former technical writer, I know that you can’t get anybody to RTFM), and so the FLOOR TEMP light just confused them.

The Italians took a different approach. Fiats, Ferraris, and (I’m pretty sure) Alfa Romeos of the late 1970s got this lovely and equally confusing “SLOW DOWN” idiot light to warn drivers of overheating catalytic converters; at least this light gave the driver some idea of the remedy for the problem. Some Fiats and British Leyland cars got a similarly cryptic (yet technically more accurate) “CATALYST” idiot light. Perhaps a really big idiot light reading “CATALYTIC CONVERTER OVERHEATING — SLOW YOUR ASS DOWN OR PERISH IN FLAMES!” would have been best.



Comments
Join the conversation
2 of 47 comments
  • GS650G GS650G on Mar 19, 2012

    Ford enriched the mixture in their carbs at idle in an attempt to cool down the cat. The 300cu six I had with an electronic carb has a solenoid for this purpose. I didn't think it worked in any case.

  • SoCalMikester SoCalMikester on May 03, 2013

    I always thought it was running too LEAN that cases the cat to glow. Or the exhaust.

  • Ajla Trucks and SUVs had taken over the consumer market by this time so these weren't quite to the risk level of the '85 Taurus but doing a nonpremium RWD tweener size car in the mid2000s was still a bold move as that kind of vehicle had been dead since the mid 1980s. Pulling it off with a unit cost comparable to a Panther or W-body was the biggest success though. The difference between what GM spent on RWD cars between 2004 and 2022 versus what ChryslerCo spent in the same period must be huge.
  • Tailpipe Tommy Ask Tyler Hoover, Jason Cammisa, Joe Raiti, Sreten @ M539 Restorations (he's really spectacular), and oh yeah, that Doug DeMuro cat. For better or worse, automotive journalism has moved to YouTube.
  • Ajla A lot of journos liked to sh*t on the NAG1 but I never had an issue with its performance and the forums don't really show it as a trouble spot by the time it got into these. It probably needed just a touch shorter gearing in base form (I think the Magnum offered that on a tow package and the Charger offered it with a performance package or Daytona trim).
  • Fahrvergnugen NA Miata goes topless as long as roads are dry and heater is running, windscreen in place.
  • 3SpeedAutomatic As a side note, have you looked at a Consumers Report lately? In the past, they would compare 3 or 4 station wagons, or compact SUVs, or sedans per edition. Now, auto reporting is reduced to a report on one single vehicle in the entire edition. I guess CR realized that cars are not as important as they once were.
Next