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Inaccuracies in manuals

A follow-up on my oil pressure switch replacement (1990 K1500 5.7L): works great now- thanks for the help!

BUT, my manual (1990 GM Service Manual- "the big one") said the switch was located on the driver's side, above the oil filter. The Haynes manual said the same thing. Looked at that location: there was a hole alright- and it was threaded for the switch- but it was empty.

First thought: someone removed it and plugged the hole Second thought: couldn't be b/c the gauge is working, only inaccurate

2 hours later, went to the least helpful manual I have just to see if something was different in Chilton's: voila! It indicated the switch was on top, by the distributor! Bingo! The third manual wins!

My ex always thought it was weird that I had different manuals on the same vehicle but here was a good reason why! Anyone know when the change occurred? Would a 1991 GM service manual be more accurate for a 1990 K1500?

Thanks again to everyone who helped with the problem!

Tim Bluff City, TN

Reply to
Tim Urbin
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what's the build date? might be a running change... hth

Reply to
StyxNStones®

My 1991 GM service manual (for my 1990 GMC Jimmy/K5) shows it located on the edge of the engine "shelf" by the fire wall, just to the inside of the driver's side head, next to/to the left of the dizzy.

GMC Gremlin

Reply to
GMC Gremlin

FYI

my 1992 K 1500 5.7 has the oil pressue switch up by the distributor, which I belive has been a farily common location on 350... By the way they are a pain in the ass to get to.

Elbert

Reply to
Elbert

Definitely a pain. While I was removing it, I kept thinking "what kind of [insert favorite word when frustrated] engineer designed this!" A wrench could move about 1/4 of an inch at a time.

So far, all the feedback I've gotten indicates EVERYONE has it next to the distributor, models earlier and later than mine. Pretty strange. Never-the-less, there is a threaded hole above the oil filter where two different pictures show it should be- maybe it was an April fool's joke!

Tim Bluff City, TN

Reply to
Tim Urbin

my '88 K2500 has the OP sender above the oil filter and the OP switch up next to the distributor.

-Bret

Reply to
Bret Chase

Bret Chase wrote: snip

Is the OP switch used only in the fuel pump circuit & the OP sender only used for the gauges? Didn't realize there were 2 separate devices.

Reply to
Stephen Young

yup

depends on the year actually. on later vehicles it's a combined unit up next to the dizzy.

hth, Bret

Reply to
Bret Chase

not if you have a van. :-) 4.3 liter is the same

Reply to
Kiel Uyttenhove

Dumb question time; What does an oil pressure switch do?

Jay

Reply to
Jay

it acts as a backup circuit for the fuel pump relay.

-Bret

Reply to
Bret Chase

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