1977 20r toyota exh temp indicator light goes on\off???

can anyone help explain its warning function. there's nothing in the
book or google. i'd appreciate any help. tks...

In article <26408-43D89752-179@storefull-3275.bay.webtv.net>,
[email]jessisin@webtv.net[/email] (zvx-JESS-zvx) wrote:
[color=blue]
> can anyone help explain its warning function. there's nothing in the
> book or google. i'd appreciate any help. tks...[/color]


According to an emissions schematic I have for 77 20R, the signal that
energizes this warning light comes from the thermo sensor in the catalytic
converter via the emissions computer. The schematic also indicates the
converter temperature range of 1562 F thru 1688 F being relevant but I
can't tell from this if the warning light illuminates in this range or if
the converter heats up beyond this range (this would be my assumption).

What is also not clear is what malady is indicated and what course of
action is required in both the short term and long run, when the exhaust
temperature warning light illuminates.

If your 20R is in a 77 pickup it must be from California as anywhere else
there is no catalytic converter in the 77 truck.

Hope this helps.

Dennis