CK5
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Yank Tank Molotov/3+3, 454/magnum/Allison
- Thread starter SpeedlabDan
- Start date
'84 K30 Silverado "big Dooley"
beags86
Eastbound and Down
I don't fully understand the flying anvil, but it's much better now
It's symbolism. Something that large and heavy that shouldn't fly.
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So it appears I was at 51psi or so so luckily I have the adjustable regulator. Few turns and I got it up to 67 or so and it's better so I put the interior back together and bolted the seat belts down.
Definitely a bit more powerful but still not right. Took it down a back country road and it's not shifting! Got up to 50mph at 2800 or so I'd guess I'm in 2nd gear which would explain why it slams into drive from neutral? I still don't know exactly why the tcm is requesting illumination but it's definitely not functioning properly. I dunno what do do at this point
Definitely a bit more powerful but still not right. Took it down a back country road and it's not shifting! Got up to 50mph at 2800 or so I'd guess I'm in 2nd gear which would explain why it slams into drive from neutral? I still don't know exactly why the tcm is requesting illumination but it's definitely not functioning properly. I dunno what do do at this point
If there is a problem with the Allison it defaults to 3rd gear and kicks line pressure to max. That's why it's slamming between park to drive or reverse and not shifting.
Got to go find the codes setting for the trans. Are you running a separate TCM or is the PCM running the trans too? Most common thing we've had on early Allisons is the external range switch on the side of the trans. They were prone to getting water inside and scrambling signal for what gear was requested. The controller be it separate TCM or the PCM need to see the requested gear or it goes right to default.
Got to go find the codes setting for the trans. Are you running a separate TCM or is the PCM running the trans too? Most common thing we've had on early Allisons is the external range switch on the side of the trans. They were prone to getting water inside and scrambling signal for what gear was requested. The controller be it separate TCM or the PCM need to see the requested gear or it goes right to default.
i was just going to say limp mode .
i have drove c4500 and c5500 trucks with 8.1 engines and allison they tip the scale empty almost 13,000 lbs that i drove . they move real good with them engine .
you got a code problem making it go limp .
i have drove c4500 and c5500 trucks with 8.1 engines and allison they tip the scale empty almost 13,000 lbs that i drove . they move real good with them engine .
you got a code problem making it go limp .
AHHH is see! When I had howell EFI separate the trans harness and put it back in with the new harness to run the Allison tcm they left a pigtail for the shift selector/range switch. After a phone call they said the large plug that is pig tailed is all outgoing to the ecu that I wouldn't need. I was kinda hoping they were right but it definitely raises an eyebrow.
I am using the factory Allison tcm and I checked all the pins are in place. So it's possible I'm not relaying info back to the tcm/ecm? If so where can I find the info as to what I'm missing? Right now the only thing plugged into the range switch is the smaller lower plug. I'm glad you said it defaults this way as it explains what I have goin on but now I need to correct it
What do you have to plug in and talk to the truck? Plugging in and reading the codes and looking at the data should tell you what is missing.
I still have the low speed data connection /obd2 on the harness. I'm unfortunately only working with a low end hand held by Innova. In advanced settings it says the tcm is requesting illumination and that's all I have. My buddy has a good reader at his shop but he's a bit of a drive in limp mode. I posted up in the garage just to see if anyone has encountered any of these issues.
What goods a Tow Pig with nothing to tow?
Got a trailer queen k5... Jus sayin lol
Just don’t leave it mothballed too long. Time slips away. Mine sat for 3 years and it seemed like a couple of months.
Oh if you know me I'm a lunatic I don't let the grass grow under my feet. It'll be back in a week or two
Yep you need to talk to the TCM. It's probably got a P0700 code set in the PCM which is the TCM request to illuminate the SES light. Ideally you'd be plugging in with a Tech2 to get right down to the point, but that isn't realistic unless you got a buddy at a dealer. But a higher end aftermarket unit should get you in.
The whole point of the exercise is seeing the TCM codes and being able to look at the data stream to make sure you have all the inputs you need to run.
You mentioned having only one connector at the range switch. A small one if I read that right. You need to have both connections by looking at the stock GM schematic. The smaller of the two is noted as C2 and it will only have 2 wires to it. One is ground and the other leads back to the PCM. The other plug is C1 and it should have 4 wires going to it. Those wires are the ones going back to the TCM for the range input. If you don't have that the TCM won't know what gear you grabbed. You might want to see if that plug in your harness matches that unused plug on you range switch.
I don't recall a two wire plug the smaller has 4-5 wires and the larger more like 20.
Which harness would it go to? Right now it's just loose wires. I'll get a pic of what's goin on to show
OK here's a couple shots. The white plug is what came back with the harness. The Grey larger plug is what the sent back. Now maybe they meant its not needed to run the ecu properly and possibly they aren't taking into account the trans needs these signals. I also tried to show the colors as best I could. I really hope the didn't leave this out but if they have I need to hook this back into the harness but to what?
It doesn't appear that the large plug has much to tell the tcm unless the nuetral/park switches throw the tcm into action?
Yes, the larger connection is the one that has the 4 wires we need to know what gear it is in. Look at the schematic.
The reason the PCM has an input is so that it can know if it's in Park or Neutral to account for the load of the trans/torque converter. Looks like they got that set right in the harness.
So is the larger connector not wired into the harness?
So is the larger connector not wired into the harness?
Those 4 wires are 5,6,7,8 that are in the white plug if I'm understanding this schematic. Honestly I'm a bit confused by this schematic. Is the orange and black what's not connected or the black/why but I'm not sure where they need to go
