Does this generation Small Block have the same issue as the old Vortec 5.7? (Intake Gasket leaks, coolant dripping into the crankcase mixing with oil)
I thought these were new enough to not leak there
What did you do to your NNBS GMT900 Tahoe/Yukon Today?
- Thread starter phattyford
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I thought these were new enough to not leak there
noDoes this generation Small Block have the same issue as the old Vortec 5.7? (Intake Gasket leaks, coolant dripping into the crankcase mixing with oil)
I thought these were new enough to not leak there
the only reason generally to pull the intake on these is to do vlom work or maybe do the oil pressure sensor since it is in a rather difficult spot behind the intake but can be done without pulling the intake off
the gmt800's knock sensors are under the intake so it has to come off, on the gmt900's they are on the outside of the block
the gmt800's knock sensors are under the intake so it has to come off, on the gmt900's they are on the outside of the block
Sparksalot
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Drove thecopcar a while today. I've notice a few random times the cruise wouldn't engage. Today it would drop out of cruise intermitantly. Tapping the brakes reset it, and away we go again. I'm guessing it's time for a brake switch change.
no codes for anything?
Sparksalot
Supporting Member
Good point. I'll have to see if my scanner will read anything.
check the historical if nothing current as it could maybe point towards something
historical codes can be a rabbit hole though if nothing looks related just ignore them mine has some that never go away and have always been there even if cleared out they magically re-appear and nothing is wrong with it.
Sparksalot
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mikez71
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bypassed the ambient light sensor. Hooked up a 680 ohm and 10k ohm resistor to a relay harness. Triggered relay with trailer parking light fuse in fusebox. (the fused side, terminal furthest from cab) though im not sure if 18 gauge wire is enough to pop the stock 15A fuse, or if my wire would burn up with short) I might add a tap and put a smaller fuse in, though the wire is loomed up and in safe locations..
red wire (30 terminal) goes to the white wire in ambient light sensor (i de-pinned it and heat shrunk the wire on it in case it didnt work)
blue wire went to brown park lamp circuit (fusebox in my case)
all other wires are grounds, but two (87a and 87 terminals) with resistors soldered inline and a bunch of heat shrink to keep them from stressing the resistor leads.
no more dimming in the daytime, adjustable dimming at night.
UPDATE: One weird behavior.
When turning lights off, the dash display goes from nighttime dim, to off, then on daylight bright.
Does not cycle off when going from daytime to nighttime.
Not sure why, maybe the sudden change in voltage going from 10kohm resistance suddenly to 680ohm is too fast for the BCM to adjust?
That or some other electrical behavior I don't understand.. Any suggestions on how to wire a fix?
Reading up on something called a flyback diode.. something about voltage spikes when power to coil is cut, which would make sense why it happens turning lights off.
Ordered a relay with diode, but I'm not sure that's the issue.
also swapped my 85 and 86 (coil terminals) around. Sounds like conventionally 85 is -, and 86 is +.
red wire (30 terminal) goes to the white wire in ambient light sensor (i de-pinned it and heat shrunk the wire on it in case it didnt work)
blue wire went to brown park lamp circuit (fusebox in my case)
all other wires are grounds, but two (87a and 87 terminals) with resistors soldered inline and a bunch of heat shrink to keep them from stressing the resistor leads.
no more dimming in the daytime, adjustable dimming at night.
UPDATE: One weird behavior.
When turning lights off, the dash display goes from nighttime dim, to off, then on daylight bright.
Does not cycle off when going from daytime to nighttime.
Not sure why, maybe the sudden change in voltage going from 10kohm resistance suddenly to 680ohm is too fast for the BCM to adjust?
That or some other electrical behavior I don't understand.. Any suggestions on how to wire a fix?
Reading up on something called a flyback diode.. something about voltage spikes when power to coil is cut, which would make sense why it happens turning lights off.
Ordered a relay with diode, but I'm not sure that's the issue.
also swapped my 85 and 86 (coil terminals) around. Sounds like conventionally 85 is -, and 86 is +.
Last edited:
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