I'm using the C5 cluster in my C4 LS1/T56 swap and I was wondering what sensors that are not part of the "main" power train control and serve as warning indicators? For example, I think the low oil, low coolant, low washer fluid, and oil temp fall into this category . What about some more? Are the sensor reading for oil pressure, coolant temp, fuel level, and Battery readouts run directly to the cluster or does something else process the data first and give the cluster info?

What does the cluster get from the one serial data wire going to it and what does this seiral data wire ultimately connected to for its data? If you know anything about this stuff please chime in because I'll be wiring my car up next weekend and I would really like to have all sensors and the cluster working 100%. Thanks

Scott

 

Tryin again.... someone has to know something..

 

I don't know a lot about the IPC data buss but I can tell you a few things I have learned the hard way! The class 2 data buss (serial buss) for the IPC is the same as the OBDII data in the OBDII connector under the dash, it is the exact same buss. I can tell you that the BCM is highly integrated into the workings of a C5. You may have problems trying to use the C5 PCM and IPC without the BCM and EBCM. I don't know why, but as soon as IPC communications are lost on a C5 it will immediately go into reduced power mode. That tells me the IPC for some reason is highly integrated with the EBCM and the PCM. Most of the gauges and many indicators appear to be controlled by the data buss. I can also tell you that feeding 128VAC into the IPC on the data buss will damage the IPC, but not always beyond repair, it is highly recommend you don't try this at home!

Let me know if you don't have C5 manuals, you will need them!

 

On the dash harness I have I traced the data bus to the "star" connector I think it was... the data line was connected to like 10-15 other wires so I would think you are right in believing there is one data bus.

In my application I have a Speartech stand-alone engine/PCM harness so it doesn't care about the IPC or BCM/EBCM. I'm pretty sure the IP will have all of the basic analog functions and basic indicators (depending on what I wire) but for the DIC and more OBDII oriented warnings/indicators I'll have a hard time getting to work. I looked at a pin out of the cluster and it looks like the gauges will work properly if you have the sensory data coming to the cluster on the appropriate pins. I guess I'll see if this is correct soon enough.. lol

I don't have manuals for a C5. and I sure as hell didn't want to buy them. I don't even have a C5... its a C4 that just happens to be a "hybrid". If you have pdf's of a few critical areas for my problem from a manual... hook a brotha up.

 

Ouch! Without the class 2 data I think the only gauge that will work is the voltmeter. Any chance the Speartech unit supplies any class 2 data, I would guess not. Trust me on this one, after sending 128VAC into my IPC (Instrument Panel Cluster) I have been working on my IPC a lot lately , and there is no input on the C5 IPC for the fuel gauge, coolant temp, or oil pressure sensors. All those sensors are connected to the PCM and the PCM sends that data to the IPC on the serial buss. Now you may be able to open up the IPC and gain direct access to the meter movements and drive them that way, or even replace the meter movements with aftermarket movements. Oil temp sensor signal is brought to the IPC, but there is not even a gauge for that. They do send a RPM signal to the IPC but the manual indicates that the tach is controlled by the class 2 data. The RPM signal may be used for the tach in the HUD. The speedo should work as long as you feed it 4000 pulses per mile. Yes, you are correct the IPC is attached to the class 2 buss at Star connector 1 pin G, gray wire on a 01 C5. All the other wires in the Star connectors goes out to all the other computer modules in the car, up to 12 I believe depending on what options you have. There is a second data buss on the C5 which is the "Entertainment and Comfort" buss but your conversion should not involve that buss at all. If you can make the IPC work you should be able to make the HUD work, did the C4 ever have a factory HUD?

 

Holy crap.... I don't really have a choice in this one. I will HAVE to find a way to get the cluster to work because I already have a C5 Dash (cut and modified to fit in my C4), complete cluster, radio bezel, kick panel, glove box, etc. etc.... This is going to be fun I can tell.

The C4 never had a HUD to my knowledge... I'm glad I didn't buy one for my swap because I wouldn't have had room for it anyway (not to mention this big IPC problem)... grrrrrrrrr

Replied to your email SpeedyZ

 

I guess I'll need to know the absolute MINIMUM items I will need to get this damn thing to work... lol I don't want to spend another $1000 on crap just for the IPC to function... That's my luck...

 

That conversion sounds really cool. Do you have any photos of that conversion. You might search the forum, someone was trying to install a C5 IPC in a pickup if I remember correctly. You may be able ask him if he ever got it to work. It was probably at least a year ago. I wish I had an old IPC to play with, I have always wanted to know exactly how they worked, specially the DIC (Driver Information Center). But I don't want to blow mine up (again) experimenting. It seems you should be able to shoot the data to it from some other device but it may require seeing the keep alive messages from the PCM, EBCM and BCM. Hard to guess without just getting in there and seeing what data it really needs.

BTW: Your quick, looks like you have done that before! Quick connection too, wish we had that kind of connections around here!

 

I guess I'll have to start messing with my cluster... I'm really good with electronics in general so i'm not scared. The time it would take me to find someone who has done something like this I could probably have it all figured out anyway.

I have done "that" before. Computers are my second love...next to my car. lol

Here are some links to my conversion... its still a work in progress but I got the engine and driveline pretty much done.

Under the car
Dash mock up after cutting
Driveline
Shifter area

 

Here are two links to the IPC Indicator and Gauge descriptions. For each of the indicators and gauges, it lists the module that provides the info, the signal line used to deliver the info and various other info regarding the gauge or indicator

http://bbengineer.home.comcast.net/d...Indicators.pdf
http://bbengineer.home.comcast.net/d...IPC_Gauges.pdf

Here is a description of the sleep/awake state for the IPC:

Let me know if you have any questions and I'll attempt to answer them for you

BBEngineer

 

bbengineer, that was the quick and dirty of what I needed! Looks like I will beable to get everything to work pretty easily after all. The only question I have is about the serial data line. There is only one serial data line that everything is connected too right and from what I gather it functions like a network hub (in its connectivity function anyway)... when one device "talks" on the line every device on the serial data line hears it. Is this how it works? Thanks again

Scott

 

Yes, it's a single bus in a star configuration (at the splice pack).

It works similar to ethernet (conceptually at least). The messages arrive at all modules that are connected to the star and the module filters based on the addressing information, or based on message type.

The only exception to this is for things like the CD changer. There is a dedicated Class-2 serial line between the radio and the CD changer.

My only concern is whether or not you need a BCM to be the Class-2 master to get things going, or if the PCM and IPC can communicate without the BCM... I'm not sure on this point...

If you don't already have them, I'd suggest getting the Service Manuals for a C5 as they will be invaluable when it comes to connector pinouts and wiring diagrams..

Another helpful piece of gear would be an OBD-II scanner that allows you to snoop in raw mode so you can see the raw messages on the bus. If there is a message that is not being answered, you could build a small circuit around a PIC and an OBD-II interface (check out the ELM serial OBD-II parts) that could respond to the messages (similar to what a window valet does). I believe that the Harrison Engineering scanner will do this for you ( http://obdscan.net/ )

Good luck and keep us posted

BBEngineer

 

Well, if it looks like I'll need the BCM I can get a new one for $200 which isn't too bad.... My entire C5 dash conversion is still much cheaper than doing an Autometer dash like I was going too. lol I do have C5 manuals... thank god and another good friend.

Can you tell me what the DLC (Data Link Connector) is? This appears on the basic diagrams I had before I got manuals. The serial data line always runs to the DLC in basic block wiring diagrams for the IPC.

 

The Data Link Connector is just a Splice Pack or Star Connector...

There is nothing special to it, it's just a mechanical connection point for all of the Class-2 serial lines.

As far as the BCM goes... I'm not sure what else IT would require to work correctly once it's installed... hopefully, you won't need one

BBEngineer

 

Its looking better and better so far Thanks for all of the help guys!

 

I just re-read your post above, I misunderstood, I thought you were running an aftermarket fuel controller, but you are just using a aftermarket harness and factory GM PCM, is that correct? That will make things a little easier. I tried looking at the Speartech web site but it is totally screwed up to view with my setup. From things I seen on other sites talking about Speartech it seems they offer special programing for the PCM. Which may be exactly what you need in your case. Are you using a C5 PCM or one from something else like a F-body?

One problem I see is how the C5 PCM is tied into all the other controllers. Like for example the EBCM. There is a dedicated PWM signal sent from the EBCM to the PCM indicating how much power the Brake control thinks the PCM should be supplying, and in return the PCM is sending a dedicated PWM signal back to the Brake control telling it how much power it is supplying. This is where special program could easily take care of a problem like this. It also probably would not be too hard to fake the PCM with another signal, tie the line high or low may work, looping the output back into the input may work too. The other problems is things like the BCM, it is the master power control module but that may not affect you any, the IPC does have a switch power signal to power it up. I would stay away from the BCM if you can! That looks like another entire mess to make work!

Another good resource for scan tools is http://www.elmelectronics.com which is the makers of the ELM322 chip which will convert the class 2 data stream into RS-232 data. The people at http://www.scantool.net makes some cheap scanners that use the ELM322 chip. They used to sell a really cheap scantool kit which was a board with no case. Looks like you can still buy the boards and chips from the in their parts section and put it together your self. Look around on these two sites, they have some really good links to good information. I have a couple of the scantool.net scanners and they do work pretty well.

The class 2 data buss used by GM is a single wire buss that idles at 0VDC and is pulled up to around 7.5VDC by what ever device wants to talk on the buss. http://www.systemconnection.com/down...Whitepaper.pdf is a pretty good paper describing how the buss works.

Before you get too far into this (like your not already pretty deep ), I would call the Speartech people and talk to them about their harness and PCM programing. It is all going to depend on their harness which OS the PCM will need to have. I'm pretty sure for example the F-body's don't run the oil pressure to the PCM, it is sent directly to the cluster. Meaning you will probably need a C5 OS in the PCM, which means the harness you use will need the oil pressure hooked to the PCM. Otherwise I don't' think the PCM will supply the data you need on the buss.

You are a brave man taking on a project like that! So far it looks very impressive! One way or another I think you will make it work.

Good luck!

 

I am using a factory GM 99 vette PCM and I had Speartech make a standalone harness and wire the additional pins that that the IPC needed. Looks like I can just tie the IPC to the PCM throught the serial data line and the other direct-link sensory items the IPC needs... everything else looks to be comming to the PCM so it can "relay" it to the IPC such as VSS, TAC, fuel, and a couple others I think... This is looking to be pretty easy after all. And I'm not going to touch the BCM with a ten foot pole if I can help it. lol

 

Oh, forgot to mention that I am having the PCM programmed for my application as well (no emissions and all other items not needed).