1985 Caddy Limo - Engine swap with transmission issues

[BlackBettyLimo]

Update: I got dragged in to a major work hole the last few weeks but managed to finally spend a weekend on the limo.

Since it's been determined that my existing engine harness is to be scrapped, I bought what I was told was a used OEM '94 replacement.

Attachment 9763

Last weekend I started cleaning it up and tearing it apart, and tagging all the plugs, etc

Attachment 9764

The problem came when I was checking out the PCM connectors and noticed a few wires that weren't listed in the Service manual.

Red PCM connector cavity one has yellow wire. This runs to a three wire connector. One of the other wires is listed as Distributor Reference Low Signal.

Attachment 9765

While we were trying to figure this out we noticed that the split plug for the coil were not present. They look like this on my current harness

Attachment 9766Attachment 9767

On the new harness the Blue PCM connector has two knock sensor signal wires on separate circuits one in cavity 22, and the other in cavity 21(which is not listed in the service manual).
The existing has the two knock seasons on a "Y" connection.

Also, Blk connector cavity 22 is empty. According to the service manual this should be a tan/wht wire for the TCC temp switch signal.

Based on the above, can anyone tell me what year this harness is actually from? The omission of the coil wires seems to be an indicator, no?

Thanks,
Cory

[BlackBettyLimo]

I'm still trying to identify some of these

Attachment 9768
ABS, right?

Attachment 9769Attachment 9770Attachment 9771Attachment 9772Attachment 9773Attachment 9774Attachment 9775

[dave w]

I would use an ohm meter to see if any of the unidentified connectors go to the PCM, and figure out what the connector does based on the pin location at the PCM. I think you will find most of the unidentified connectors do not go to the PCM, and are "Chassis" wires. One method I use to quickly figure out if a connector goes to the PCM is slide the ohm meter (set to diode beep sound) leads across PCM pins. If I hear a beep sound I know the connector is wired to the PCM.

dave w

[ScottP]

Cory,

What you have there is a '96 B-body harness. The dead giveaways are:

1 - The 3-pin Metripack 150 connector you have labeled as Dist Low is the crankshaft position sensor.
This was only found on '96 B-body harnesses and was used for misfire detection. The 94-5 B-body LT1
harnesses did not have this.

2 - You have two separate knock sensor inputs on Blue 21 and 22. This too was unique to '96. The knock
sensors come in on two separate pins in '96 to comply with the OBD2 requirements for fault detection.

3 - The ignition coil connector on your new harness doesn't match the 2-piece version you show above.
Again, this was a model year 96 change for the B-bodies. The '96 LT1s used a new ignition coil with a
3-pin Metripack 150 series connector. This coil is also commonly found on the Vortec L30 and L31 engines.

In IMG_7655, the long connector with the stainless latch and big rubber boot on it is indeed the ABS module connector.

In IMG_7669, from left to right you have the ABS module ground, (4) PCM connectors, washer fluid level, MAF connector and washer fluid pump

IMG_7674 and 7675 are the wiper motor connectors

IMG_7681 is one of the front wheel ABS sensors

IMG_7687 The unlabeled 3-pin connector is for the ignition coil, and the one with the orange and black wires is the power steering pressure switch. The red and black wires are part of the AIR system.

IMG_7690 is the ignition coil connector

IMG_7691 show the 4L60E transmission connector (the big one), the VSS connector (violet and yellow wires) and one of the rear O2 sensor connectors.

Good luck with your repair.

-Scott

[lionelhutz]

#1 looks like ABS
#5 is not EFI related. It might be an ABS pressure sensor?
#8 looks like an O2 sensor connector.

Strip the harness enough you can figure out where the connector wires go. Label each connector and figure out where the wires go.

Most of the wires that don't go between a connector and the PCM are not required. You will have wires that come from the PCM connectors and don't go to another connector for a sensor. You may also find some sensor/solenoid/etc connectors with wires that go to the PCM except for 1 or 2 wires. You have to sort those wires out and figure out where they have to go. Mostly, I would expect these to be power or ground wires.

You have a full harness so you have gauge sensor wires, ABS wires, possibly heater wires or windshield washer wires etc in there. Once identified, you should start removing those wires and connectors. For example, take the main ABS connector and pull the wires out any place they go to another connector. Any of that wiring can be removed. I would pull the extra wiring out as much as possible in one piece and then chop off any extra wires still attached into the "good" harness leaving them long on the "good" side of the harness. If you then determine they aren't needed you remove them completely too. In other words, first pass is just to pull out any blatantly wrong wiring and connectors and eliminate as much obvious extra as possible. Second pass start sorting out what is left and remove what still isn't needed. The the third pass should get you close to a harness you can start to bundle back up and use.

[BlackBettyLimo]

Thanks dave w, ScottP and lionelhutz for the great info and suggestions.

Agreed that a tone/ beep Ohm meter is very very handy. I've been using one to find the plugs that I have identified to-date, and to diagnose the issues with the old harness.

Thanks for the identification of the remainder of the plugs. I was pretty embarrassed that it took me 6 hours of clean up and chasing wires before I noticed this harness didn't have the right coil wires. I've got to stop the blind assumption that everything I buy is going to be correct. By the end of this project I may know thing or two about an LT1 swap, haha just in time.

I called the guy who sold me the harness and he was pretty embarrassed that he had misidentified it for sale and he's willing to take it back. So I've got that going for me which is nice.

But this puts me at a crossroads with the million dollar question: Do I try to convert this '96 harness back to a '94, or, do I try to hunt down a used '94 harness and start over?

This one only cost me $100 and most other used ones are $200+, and my project funds are evaporating fast.

It seems I would only need to pull the coil circuit off the existing harness and swap it out on the '96 one. Except for the knock sensor circuit I have yet to research how much more of a pain it would be to modify it to work.

I'm off to the limo tomorrow to stare at it for a few hours and try to wrap my head around it.

[ScottP]

The '96 harness can be converted to '94 fairly easily, and the differences between them are fairly minor.
Some of the notable ones include:

'96 adds the crank position sensor and CCP flow switch (these go to pins that are not used on the 94-5's 16188051 PCM)
'96 has two separate knock sensors that come into the 16214399 PCM on Blue 21 and 22, where the '94-5 harness brings
both knock sensors in parallel on Blue 22 only.
'96 changes the ignition coil connector

These minor differences are what allowed '96 owners (like myself, quite a few years ago) to swap out the '96 16214399 PCM
for the 16188051 back when OBD2 flash/tuning tools weren't available. My 96 PCM went right back in once TC released his OBD2
package many years back.

I think the bigger issue with the harness you bought is that the entire underhood relay and fuse center was cut off. That means
you will need to extract it from the harness you're using now to make it "whole" again.

You may want to keep debugging what you've got - seems like you might be close? To that end, here's some
tests you can run to try to eliminate your DTC43.

First, inspect the Blue PCM connector - is there a dark blue wire in pin 22? There should be - that's the connection
to the knock sensors.

Next, using a DVM set to ohms, measure the resistance from the dark blue wire on pin 22 to engine ground. It should
measure ~1.95kohms. Each of the '94-95 knock sensors on a Bbody LT1 are nominally 3.9kohms each. In parallel, they
should measure 1.95k. If you get a substantially different reading than this, its the cause of DTC43 and is also why
your fans are running.

I bet with just a bit more guidance, you'll have things running well!

-Scott

[ScottP]

One more tip I just dug out of the mental archives.

Bbodies used two knock sensors in parallel on Blue 22 from 94-5, while Fbodies only used one.
This means that the test criteria for DTC43 is different depending upon whether you start with
an Fbody calibration or a Bbody calibration. If the tests I outlined above don't reveal any
problem, its possible that you have an Fbody calibration. A very easy way to test this would
be to unplug one of the two knock sensors and see if DTC43 goes away.

-Scott

[BlackBettyLimo]

One more tip I just dug out of the mental archives.

Bbodies used two knock sensors in parallel on Blue 22 from 94-5, while Fbodies only used one.
This means that the test criteria for DTC43 is different depending upon whether you start with
an Fbody calibration or a Bbody calibration. If the tests I outlined above don't reveal any
problem, its possible that you have an Fbody calibration. A very easy way to test this would
be to unplug one of the two knock sensors and see if DTC43 goes away.

-Scott

Thanks Scott, very helpful.

The existing harness I have has a broken Blue PCM plug, which someone prior has epoxied shut. They managed to put the knock sensor pin in the wrong location before doing this. So if I continue with the harness I have and want to make the knock sensors work again I'd have to address that.

Based on all of the above it may be worth the extra effort to just convert this harness. I'm headed out to the car now to check it out. Thanks again

[BlackBettyLimo]

Took the plunge and started the conversion of the '96 harness. Thanks to the help I was able identify and remove quite a few component plugs/ wires (ABS, wiper, washer, Low Dist, etc, etc). I'll pin out the rest of the harness and tag the remaining wires tomorrow. It may be a week before I can get back to the car and graft portions of the existing harness into the '96, but at least I'm headed in the right direction.

[BlackBettyLimo]

Hey guys,

My buddy and I have made some really good progress on the harness the last 2-3 days. It's almost fully installed and we are finishing taping it all up. I forgot to take a pic but it looks nice and clean/ factory now.

The good news is that the cars starts right up and "runs". The MIL light no longer stays on and the fans operate normally. The primary fan stays off until about 185º, then kicks in. The 2nd fan didn't kick on during our short idle (no road test yet)

The bad news is I didn'tt have my laptop with me and I was still running the old bin file supplied earlier (with EGR and CCR off, etc). We began to notice that the car was now having hard time idling and we are hearing pinging. Almost as though it was running lean? Honestly not sure why. Since everything is "turned off" in the bin it should run like it did before, no? Unfortunately I didn't have a computer to check out the data stream.

At this point what I'd like to do is upload a modified version of the attached bin file. I think the hearse bin is ultimately the best match for my setup. The only issue is I don't know how to change the tire height and rear gear ratio using Tuner Pro.

Kur4o - Any chance you can list the steps , or PM me, so I can learn how it's done (I'm also using the EEX file you gave me)?
Or if that's not a reasonable ask, could you please help and adjust this bin?

I'm headed out to the car tomorrow morning, so hopefully I'll be able to upload a new file and see if that clears up the way it's running. I'll do some logging and post results.

Here are the current changes I've made to the heres bin so far:

11/20/2015 19:36:55 Flag: * AIR Pump Enable changed from Set to Not Set..
11/20/2015 19:39:54 Flag: * VATS Enable changed from Set to Not Set..
11/20/2015 19:41:32 Flag: Vss Signal Diagnostic (Error 97) changed from Set to Not Set..
11/20/2015 19:41:50 Flag: VATS Diagnostic (Error 46) changed from Set to Not Set..
11/20/2015 19:42:00 Flag: Traction Control Diagnostic (Error 74) changed from Set to Not Set..
11/20/2015 19:43:41 Flag: * Air Pump Diagnostic (Error 29) changed from Set to Not Set..

Unless I've overlooked something everything else is "on". Rear gear should be 3.42 and tires are 28 inch (235/75R15).

Thanks!
Cory

[BlackBettyLimo]

Well, today was bit challenging. Since I haven't figured out how to adjust the Hearse bin, I thought I would just tweak the existing file and turn on EGR and CCP, etc. After making the changes and uploading the file, the car was still pinging and running like crap in closed loop mode (open loop seemed fine). I began to doubt my harness modification skills a bit.

I was monitoring using 9495 and as I started to try to wrap my head around the data stream I began to smell fresh gas. Lots of it. I looked under the middle of the limo and saw a 2 foot puddle of gas forming. After turning off the car and mopping up the mess I found that the metal hardline fuel line does not run the full length of the vehicle. A 4" piece of fuel hose joins the two sections of hardline at the midway point, and it had finally let loose. The upside is that we weren't road testing the car or even worse out for a night on the town the it happened.

Once that was fixed we got back to detective work. We notice that one of the O2 sensors was registering a very low voltage (0.03x) and the fuel corrections were not taking effect. We then got a DTC 46(?) which was the right bank O2 lean condition. At first we thought it could have been a bad O2 sensor or faulty injector, but the car was running well before the harness swap so it seems unlikely.

We started to pin out the circuit/ PCM plug and quickly realized that we had mislabeled the O2 connector on the harness. We had the left bank connector plugged into the right O2, etc. That's a good way to piss off a PCM. It was trying to make fuel corrections but the opposite O2 was seeing the adjustment.

Since we had already carefully routed the harness with zip ties and clamps, we just popped the pins in the connector and switched the positions.

We fired it back up and it ran normally, or so I thought. I was just going through he bin file and it looks like I forgot to correct some changes to the EGR Enable scalar (maxed out) I made when I was trying to bypass it. So the EGR probably wasn't working properly today.

Here are a few data logs (https://www.dropbox.com/sh/u2f79mbv4...rP67og5va?dl=0). I was getting 2 DTC codes for oil level and oil life. I just found them in a "Corvette Only" folder in Tuner Pro and turned them off.

Tomorrow I'll upload this final file and do a few more logs.

Here's a pic of our relay panel. We're still cleaning up the wiring and fabricating a bracket for the PCM.
Attachment 9812

[1project2many]

I have to applaud your perseverance in this. It's unfortunate that you are having so many problems but I'm sure you'll get it figured out.

We had the left bank connector plugged into the right O2, etc. That's a good way to piss off a PCM. It was trying to make fuel corrections but the opposite O2 was seeing the adjustment.

Years ago I had to diagnose a trade in Corvette that had been deliberately connected like this. Inevitably one bank would be driven rich while the other was driven lean. I have no idea what magic the vehicle owner thought this change would produce but it ended up running horribly. Once the correct sensor was providing feedback the car ran well.

[lionelhutz]

Sounds like you're getting there. One thing to note is do not ground the PCM. Make sure your bracket is insulated or plastic.

[BlackBettyLimo]

Sounds like you're getting there. One thing to note is do not ground the PCM. Make sure your bracket is insulated or plastic.

Oh hell. I guess the aluminum bracket we spent the day fabbing up will have go

Thanks for the heads up!