TIMMYS89GTA

iTrader: (28)

so,my 85 iroc should have the one just behind the distributor correct? Well,it does and is hooked up and no problems....but,car also has one next to the oil filter just threaded in,no wire harness plugged into it....I don't get it..I searched and traced the harness and there is no plug in for it floating around..this must have been placed there by previous owner I am assuming..as far as I remember,wasn't it 88 when GM started using the sender by the oil filter?

Tibo

iTrader: (15)

If I had to guess the year I would say 1986 when the one piece rear main seal, hydraulic roller cam blocks became prevalent. There could be a hole there, threaded or not but I was under the impression that was for linkage??

jokerZ71

IIRC'it was around 89 that GM went from the 2 wire sender to a 3 wire sender.The 2 wire sender operated the dash oil lite & fuel pump cutoff.The guage would run off of a 1 wire sender,usually near the oil filter.The 3 wire unit does both jobs.

TIMMYS89GTA

iTrader: (28)

It has the actual sensor screwed in next to the oil filter and nothing attached to it..the one on top of the block is hooked up and working like it should..my old 87 iroc had the same one on top of the block and my old 88 rs had the one next to oil filter so I was guessing that 88 was when they changed..

TIMMYS89GTA

iTrader: (28)

that may be right..89..can't recall now,thought my rs was an 88 but may have been an 89...so I'm guessing maybe someone decided to put a new sending unit in it and got the wrong one and just left it there after they found out it wasn't the right one..lol..who knows

jokerZ71

They mita just used it as a plug if it was converted from 2 wire to 3 wire.I'm assuming you now have a 3 wire & a working factory guage.They coulda also maybe been running an aftermarket guage @ 1 time with it.I'm not 100% on the year bein 89,or,if it was an across the board change.Some vehicles may have gotten it earlier,or,later.

TIMMYS89GTA

iTrader: (28)

Well just cross referenced on advance auto site and 85-88 use the style on top of the block and 89 later used the 3 wire..also noticed that the 3 wire is cheaper than the 2 wire..so possibly previous owner not knowing thought he could get by with the cheaper one?
The car has the original 2 wire hooked up and functioning correctly,the car is all original and has not ever had any aftermarket gauges..I had one other problem with the car and that was that someone tapped an ignition source into the fuel pump feed wire so pump was running constantly..and also found at the same time that the oil sender was just completely unplugged..so I am assuming they had a no start issue because of this and (fixed) it by rigging the fuel pump to run constant when key was turned on..
Thanks guys for the help