Another 1991 Suburban
- Thread starter sean257
- Start date
Gtstintpro
New member
Remote start tech sheet says white wire at the brake pedal switch should read 12v when pressed... You can use a standard automotive relay to make what you need happen..run the white wire off the brake switch to pin 85 of relay. 86 of relay to ground. 87a to 12v either battery or ignition..make sure to fuse it..ground to 87..and pin 30 will be your output wire you're looking for..if it needs to see an open when pressed instead of 0v (ground) remove the wire from 87..when brake is not pressed relay is not being energized allowing 12v to pass through..when brake is pressed it energizes the relay and switched the contacts to allow the ground to pass through now
Thank you.
Truck is running and driving now.
Problems that need worked out:
Tranny is shifting from first to high gear. I have a code p1810, I do not know if that is part of the problem, or if it is a computer problem or a tranny problem yet.
Speedometer not working. It is wired, needle moves a hair when ign power is on, but nothing otherwise.
Temp gauge not working.
Needs fan shroud.
No reverse lights.
Improvements to be completed:
AC hoses
Stereo and speakers
Cut fenders and add flares
Cargo area tie downs.
Truck is running and driving now.
Problems that need worked out:
Tranny is shifting from first to high gear. I have a code p1810, I do not know if that is part of the problem, or if it is a computer problem or a tranny problem yet.
Speedometer not working. It is wired, needle moves a hair when ign power is on, but nothing otherwise.
Temp gauge not working.
Needs fan shroud.
No reverse lights.
Improvements to be completed:
AC hoses
Stereo and speakers
Cut fenders and add flares
Cargo area tie downs.
Larry
Bigassgas Explorer
Sounds like progress is being made. No major engine swap is ever complete until at least a dozen bugs are sorted out. P1810 is a transmission related code. It could be something as simple as a connector being left loose. PM me your email address if you would like me to send you a PDF of the P1810 flow chart. This could also be related to the speedo issue.
The temp gauge should be wired the same as it was with the old engine. The coolant temp sensor in the passenger's side head is the coolant temp feed to the ECM but there is another pipe plug in the driver's side head. Just add an old style gauge sending unit in there and attach the original temp gauge wire to it. The gauge feed and PCM coolant temp feeds are separate.
The temp gauge should be wired the same as it was with the old engine. The coolant temp sensor in the passenger's side head is the coolant temp feed to the ECM but there is another pipe plug in the driver's side head. Just add an old style gauge sending unit in there and attach the original temp gauge wire to it. The gauge feed and PCM coolant temp feeds are separate.
Wh1t3nukle
I gotz dis
Just quoting a highlight post in your thread. That step is just all win! Hopefully you get your tranny issues sorted. With the gear swap are you running any tuner (I'm missing what year on the engine) to adjust/calibrate gear/tire size as well?
Thanks. He did not add any support to the roof, and it seems Ok. The rack has pretty big feet, and is trough bolted through the roof. He used 1x1x10ga tube steel for the roof rack, as well as some 1" plate that was burned on our plasma table for the transitions since we do not have a tube bender for square tube. In the corners of the roof rack he used 90 degree sections of ID/OD ring burned out of 10ga plate for the top and bottom of the "tube" and rolled 10ga for the sides. The deck is 3/4 No. 9 flattened expanded metal welded to the tube. The expanded metal is a little springy, so we'll just have to see how it holds up. Over all the rack is ~4' wide x 10' long, 11-1/2" tall in the front transitioning down to 6" The bottom frame of the rack has 4' wide cross bars every 2', and there are 2 bars splitting the width that run in the 10' direction.
Back bumper and ladder is on
I wanted a fold down step since the bumper is pretty high:
The fold down step is very solid and sturdy!
Larry
Bigassgas Explorer
If you haven’t done so already, remove the oil pressure sending unit and hook up a mechanical oil pressure gauge to verify the oil pressure. From the GM service manual the Minimum oil pressure 5 psi @ 1,000 RPM / 10 psi @ 2,000 RPM when hot. You could have a compatibility issue with the oil sending unit you are using and your actual gauge or the way it is wired.
You could actually reuse the oil sending unit from the old 5.7L and use it on the 8.1L as the threads are the same that way you wouldn’t have to change the connector at the sending unit. My OEM 1978 oil pressure sending unit connector was in pretty bad shape so I used the oil sending unit that came on the 8.1L and changed the connector for the oil pressure gauge circuit to be able to plug into the late model sending unit.
The AC Delco part number for the sending unit I am using is a D1819A
This is the connector that plugs into it. PT1825
Thank you again Larry. Now is there a trick to actually getting to the sending unit :Wow1:
Edit: I got the sending unit out and hooked up a mechanical, and I have 50psi cold. I put in autozone's version of the D1819A (PS216) which hooked to the wire I have, but the factory oil gauge is still showing 5psi
Edit: I got the sending unit out and hooked up a mechanical, and I have 50psi cold. I put in autozone's version of the D1819A (PS216) which hooked to the wire I have, but the factory oil gauge is still showing 5psi
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Update - transmission is shifting correctly only after driving for a bit after starting it. Once it starts shifting right it will keep doing so until you turn the truck off. According to the tuners logs, the input and output VSS's match perfectly when shifting normal, but when it is not shifting normal, the output rpm's are 2-3x higher than the input (input 2,000 and output 5-6000 rpm). Any thoughts on this would be great.
So I guess my oil pressure gauge is bad or wired wrong. I left the new sending unit in, and the gauge plugged in reading 5psi. I just made the mechanical gauge a little more permanent by teeing into my oil cooler lines and professionally zip-tying gauge.
Cold:
Warm:
So I guess my oil pressure gauge is bad or wired wrong. I left the new sending unit in, and the gauge plugged in reading 5psi. I just made the mechanical gauge a little more permanent by teeing into my oil cooler lines and professionally zip-tying gauge.
Cold:
Warm:
Larry
Bigassgas Explorer
Glad to hear the teething issues are getting sorted out. When doing a major powertrain swap like this there are always teething issues to be sorted through. It sounds like there is something funky going on with the way the oil sending unit is wired but you cannot go wrong with a manual oil pressure line going to a gauge like you have it now…until the cheap vinyl line leaks.
Personally, I would not even mess with that 4lo ECM signal as all that is going to do is retard timing, injector pulse, etc and reduce engine power in 4lo to prevent overtorqing the driveline when the ECM sees that signal. I am surprised your ECM tuner even wired and turned on that circuit. My 8.1L infused truck has no idea it is in 4wd, 2wd or low range nor does it need to know just like old carbureted and TBI engines had no idea what range the transfercase was in. Without studying the diagram, grounding it might just do the trick.
Pictures? Videos?
Personally, I would not even mess with that 4lo ECM signal as all that is going to do is retard timing, injector pulse, etc and reduce engine power in 4lo to prevent overtorqing the driveline when the ECM sees that signal. I am surprised your ECM tuner even wired and turned on that circuit. My 8.1L infused truck has no idea it is in 4wd, 2wd or low range nor does it need to know just like old carbureted and TBI engines had no idea what range the transfercase was in. Without studying the diagram, grounding it might just do the trick.
Pictures? Videos?