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Conversion issues, what to do next?

NoDak

NoDak

Next project - fuel mizer Suburban
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Location
Bismarck, ND
Ok boys and girls, what would you do next?

We took a gas 5.7L suburban, bought all new diesel wire harnesses ('99 vintage), flashed a '99 program in pcm, and stuffed a 6.5L in it. See signature for details.

Current status; starts, runs drives, but has a few issues;

1. Wait to start light is off while glows are lit, then comes on when glows go off.

2. Security light is on.

3. Will not shift up into overdrive.

4. Tranny lets things rev up then shifts hard as though it's in a limp home mode? All wires from pcm to tranny pass continuity test.

I suspect we'll have to buy some sort of diagnostic tool. I thought I'd pose the situation in hopes we've missed something obvious.

Other clues;

The tranny was from a '96 vintage 6.5L 3/4 pickup.

The dash harness was new but had to be converted from auto 4wd to push button 4wd.

So many things assembled at once and thus multiple problems may be in play.

I've traced and verified all the gear vender connections and modifications around the vssb. Vehicle speed seems to read correctly.

Any thoughts and or suggestions welcome.

Not sure if this is a post for 6.5L, diesel conversion, electronics???
 
Maybe I should have titled this thread "Help!!".

Doesn't anyone have some wisdom to share?
 
No, no... reflashed the '96 donor 6.5L pickup pcm. Same p/n box '96 to 2000.
 
I'm no expert but I think I wouls start by comparing wiring diagrams between the gasser and the diesel, I've also "heard" the 96 tranny electronics were more of an obd1 than an obd2. Still trying to figure that one out myself.
 
The only person who may be able to help is THEFERMANATOR (sp??).

He has transplanted D-max into 95 Suburban with 6.5L.

Not exactly the same engine but the experience in troubleshooting this type of problem may be valuable.

Unfortunately, he is in FL. Check with him anyway.
 
Did you replace engine side of the harness or incab side or both. I gauranty the gasser vs diesel pinout is different, so if you mixed them you will need a shop manual and lots of time to repin wires.
 
Ok, I'll have to study all the above comments when I get home. We are snowmobiling this week around Island Park, Idaho.

But I did have a chance to quiz a few GM guys and tranny guys that I should share.
1. The passlock is in the ignition switch (wire harness). We had to install this new as well. So, a trip to a tech2 could fix that up.
2. The tranny guys believe the '96 vs 2000 4L80E to be same except for oil cooler port locations on tranny.
3. They all suggested going for a drive with a monitor/tech tool, and see what "shift commands" the pcm is calling for, as it may be tranny issue?

Also, more info regarding above questions...
1. The following harnesses were replaced with NEW GM Harnesses (engine, injection pump, dash, tranny/transfer case).
2. The chassis harness was simply converted to handle the in-frame fuel pump and new diesel fuel tank and sender.

Ok, have I missed any questions?

Thanks for the help and I'll keep you updated as progress (win or loose) is made.
 
Hi there, back again. Been way too busy this summer. But I did get this vehicle in the hands of a competent gm guy with a tech2. Progress is slow as he has limited time and I've had to get him up to speed on all the history.

Progress thus far...

1. Found the brake pedal swith always open. New switch fixed that up.

2. Tranny overall ratio was off by a factor of 1/2. Turns out on a 2wd you need the oss sensor (tranny output speed sensor). But when you have a 4wd we need the vss (in tailshaft of the transfer case, or in my case in the tail of the GearVendor overdrive/underdrive) and they abandon the oss signal. We had both plugged into the harnesses so we were getting twice as many pulses as we should have. Thus, with this and above, the rig now shifts into overdrive.

There is still a "general communication" error. So we'll be looking into the 4wd/transfer case shift control module. Maybe the brake master and antilock brake setup taken from a '96 donor 3/4 ton pickup is an issue too?

It also takes quite a bit of brake pedal pressure to get it stopped. Perhaps the 6 bolt smaller wheels and the master cylinder taken from an 8-bolt 3/4 ton is an issue?

At any rate, we are knockin off the big items and working down to the little stuff.

Maybe soon we'll get this thing road worthy? Stay tuned, but be patient.
 
A 96 ABS module won't communicate over a 99 bus I don't believe, so that probably is your communications issue.
 
I believe that is your communication error as well. I did the same with the one I recently built and my brakes are fine.

I had trouble between prndl switches between the 95 donor and the......wait for it....2001 truck! Still havent figured it out. You can force a shift to test. Many trans shops make a control box of switches to test the trans by shifting it and locking the TCC.
 
Good stuff guys! I thought I was crazy, but countryboy69 mixing '95 and '01, yikes! I guess that would be the inverse of theferminater's project? I am pretty sure my next one will get done in Florida and it'll be a 2012 or so????

As for my rig, we got the speed sensor signal issues sorted out and it shifts into overdrive now, all should be good there.

I suspect you folks are right, my remaining electronic items on this rig will have to migrate toward '99 stuff.

The only two electronic items that are not '99 vintage would be; transfer case control module ('98 vintage) and the anti-lock brake module ('96 vintage).

Tech2 guy says he can flash the transfer case control module to the correct p/n. That outta fix that up!

We will probably have to change parts on the anti-lock brake module to '99 vintage though?

But... What about the possible mechanical differences with the master cylinder vs. brake cylinder size? The master cylinder and hydro-booster on this rig came from a '96 2500 (8-bolt) donor pickup. Everything I've done is to move toward a '99 1500 6.5L suburban. Keep in mind the '99 1500 6.5L suburbans had 8-bolt wheels right? However, this rig has the "true" 1500 6-bolt wheels with the logic of maximizing fuel economy (except you don't give up 4wd in North Dakota for fuel economy). But now I'm curious what is different between the brake masters for big wheel brakes vs. small wheel brakes (1500 6-bolt, 1500 8-bolt 6.5L suburban unique or 2500 8-bolt). I guess I need to research the parts books to compare what I have to what I think I need, which is a '99 vintage brake master and module for a 1500 pickup (with 6-bolt wheels).

We'll go do some homework on this front unless there is something I'm missing here?
 
The MC bore should be different. You should be fine to just swap out the HB unit and keep your MC.
 
MC = Master Cylinder, HB = Hydro Boost... right?

I presently have the '96 HB and MC and antilock brake module from the 2500 truck installed in project vehicle.

I still have stored away in the basement, the original parts from project vehicle which was a '99 true 1/2 ton 5.7L gaser with vacumm booster, antilock brakes, master cylinder.

I'm not sure which parts you are suggesting I swap out?

Can I mix and match what I have, or do I need to go the parts counter for some stuff.

Very much appreciate the help!!!!!!
 
Just remove the vac booster and swap in the HB, done deal. The only difference could be some HB's require a longer or shorter rod to push the MC piston. Seperate your MC from the vac booster then compair what the vac booster side (where it will engage MC) looks like compaired to your HB unit. Maybe get some pictures of them and post them. I've done several HB convertions and its pretty easy.
 
Exactly what ^^^^ said! I dont usually go this (01 reverse engineered) direction with my projects but I will explain why in the thread I will start for it. My usual is 6.x stuff and other diesels into much older trucks and a few cars. I will stay tuned to see if I can help ya when ya need it.
 
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