shawn@eddie.MIT.EDU (Shawn F. Mckay) (05/04/87)
Howdy, I wonder if anyone can help me out, I have a 1986 Chevy Camaro, onboard it has a Computer system, of unknown type, I have made several attempts to get doc on it, but the most I can get is it's made by delco, I called delco and they said they used to give out full specs on the system, rom listings, serial data stream info, and schematics on the ECM itself. However, they don't do that anymore... My problem is that I would dearly love to have this information, I purchased the shop manual for the car, but have had little luck in finding anything useful in it, in fact, I can't seem to even find the assembly blowup of the cyclops, (which has a bulb burned out I would like to replace). I would normally just give my car to my chevy dealer, but they seem to be unable to change oil correctly, never mind understand what oil does, so I am finding myself in a position of having to actully EXPLAIN parts of my car to the service people, and what the things do, this makes me very nervous since I don't know that much myself. I flamed at GM, but they are useless, as is there customer assistance program. Anyway, I have just about everything I need, but I would as I stated dearly love to lay my hands on the computer system specs/listings/any other info, as I would also like to be able to extract some useful information from it, even if just to make flashy displays on the dash. Anyway, thanks for any help you can give, and anyone know a GOOD chevy service center in the Boston, Ma area? Thanks again. -- Shawn Mckay Uucp: mit-eddie!shawn Arpa: Shawn at Mit-Mc Chaos: Shawn at Mit-Eecs
tim@ur-cvsvax.UUCP (Tim Takahashi) (05/05/87)
In article <5701@eddie.MIT.EDU>, shawn@eddie.MIT.EDU (Shawn F. Mckay) writes: > > Howdy, I wonder if anyone can help me out, I have a 1986 Chevy Camaro, > onboard it has a Computer system, of unknown type, I have made several > attempts to get doc on it, but the most I can get is it's made by delco, > I called delco and they said they used to give out full specs on the > system, rom listings, serial data stream info, and schematics on the ECM > itself. However, they don't do that anymore... The GM Delco Computer Command Module is based on the Motorola 6800 family microprocessor, a 6808 I think? The operating system is stored in approximately 32k of ROM. Much of this ROM is devoted to troubleshooting in case one of the inputs goes south, Throttle Position Sender, Outside Temperature, Manifold Vaccum, Oxygen Sensor, Engine RPM, Brakes Depressed, Air Conditining ON, Engine Coolant Temp. (Mass AirFlow is calculated from RPM, Vaccuum, Temp, and Throttle Position is some versions). Outputs that can also malfunction are handled in software; electronic injectors (fuel/air mixture), idle control air-valve, spark advance, purge charcoal cannister, open/close EGR valve, disengage Air Conditioner, etc. The programs are directly written in 6800 machine language, without a compiler and are very complicated, I wonder who knows how it really works.
rinehart@topaz.RUTGERS.EDU (Mark J. Rinehart) (05/05/87)
The only *good* Chevy dealer service center I know of is the one I dream about whenever I'm about to take my car somewhere for service. I have used 2 Chevy dealers in Jersey and they are both staffed with idiots and shady characters who barely know how to say their name, let alone change the oil (which the 1st time I had it done, cost me $50.) or perform any other more difficult service. 8-} Good luck in your search. Mark Rinehart
paulf@Umunhum.STANFORD.EDU (Paul A. Flaherty, N9FZX) (05/06/87)
In article <11756@topaz.RUTGERS.EDU> rinehart@topaz.RUTGERS.EDU (Mark J. Rinehart) writes: >The only *good* Chevy dealer service center I know of is the one I >dream about whenever I'm about to take my car somewhere for service. I >have used 2 Chevy dealers in Jersey and they are both staffed with >idiots and shady characters who barely know how to say their name, let >alone change the oil (which the 1st time I had it done, cost me $50.) >or perform any other more difficult service. 8-} Good luck in your >search. > >Mark Rinehart Hate to spoil your dreams, Mark, but even out here on the west coast, I have yet to find what I would consider a reputable Chev dealership shop. I recently took my pride and joy ('79 Z28) in because the tranny was dripping dextron. After tearing it down, they concluded that it needed to be rebuilt. I went back the next day, looked at the clutch steels, and agreed. Well, from that point, it took them nearly two weeks to finish it up. When I got it back, the tranny was rebuilt, but *still* leaking, and they'd messed up my exhaust system. Needless to say, I drove it back, and chewed on the manager for about fifteen minutes. The whole experience left me without a car for two and a half weeks, and over $1100 poorer. Okay kids, let's recite the Ralph Nader litany: "NEVER, NEVER take your car to a dealership for repairs." Not even if you have the money, and "want the job done right". -- Paul Flaherty, N9FZX >->-_->-> Computer Systems Lab -- Stanford University | Project ARPAnet: paulf@shasta.Stanford.EDU ===== OSCAR AMnet: N9FZX @ N6IIU =====
girault@COS.COM (Jacques Girault) (05/08/87)
In article <1580@Umunhum.STANFORD.EDU>, paulf@Umunhum.STANFORD.EDU (Paul A. Flaherty, N9FZX) writes: > Okay kids, let's recite the Ralph Nader litany: > > "NEVER, NEVER take your car to a dealership for repairs." > > Not even if you have the money, and "want the job done right". > Please excuse my ignorance but in the past I have always been able to perform all maintenance myself. I now have a Camaro Z28 IROC on order and from the looks of things under the hood I can't even get to the plugs. Where should the work be performed on this car?? -- Jacques --
rinehart@topaz.RUTGERS.EDU (Mark J. Rinehart) (05/08/87)
> Please excuse my ignorance but in the past I have always been able to >perform all maintenance myself. I now have a Camaro Z28 IROC on order >and from the looks of things under the hood I can't even get to the plugs. > > Where should the work be performed on this car?? > > > -- Jacques -- That's a good question. I have an IROC - 86 which I've had serviced using 3 different Chevy dealers. 2 of the 3 were schmucks who made some warranty repairs that should have been performed in one trip, if they had done the job right, but ended up taking 3 trips each time. Unless you know a good mechanic who also happens to have a CS degree, you'll be in the same boat I am right now. However, I was using a Good Year service center until recently when they moved. I've never had any complaints about them and their fees for labor and parts are cheaper than any dealer I know. Good Luck with your "Roc"! I love mine. Mark
amos@instable.UUCP (Amos Shapir) (05/10/87)
All follow-uppers on this subject: this started as a discussion of
a car's computer system on comp.misc, and deteriorated to contents
worthy of misc.consumers.autos. Please keep the discussions in
their proper newsgroups by editing the 'newsgroups' and 'followup-to'
fields in the header (see above).
--
Amos Shapir
National Semiconductor (Israel)
6 Maskit st. P.O.B. 3007, Herzlia 46104, Israel Tel. (972)52-522261
amos%nsta@nsc.com @{hplabs,pyramid,sun,decwrl} 34.48'E 32.10'Nwtm@neoucom.UUCP (05/11/87)
I had a job interview about 2 years ago to work for GM as a contract employee owned by a head hunter agency rather than GM itself. At the time, they were producing the GMP-4 microprocessor for use in their ECM. The GMP-4 is a semi-custom version of the 6809. I didn't really get a chance to see how different it is from a stock 6809. They were using an IBM mainframe and cross-assembler to develop the code. As the previous poster said, all the code is written in assembly level. The unit contains 32K of ROM, which is a lot of code to write in assembly. The listing was 4 data binders, each aobut 10-15 cm. thick. The code is very thready, and would probably be very difficult to wade through without the source (ugh!). The main loop of the control program is desgined to execute at least once every mS. Much of the code is dedicated to the so-called `limp home' modes that determine default parameters to substute when some of the engine sensors fail. There is also some on-board interface software that allows the ECM to talk to the service shop diagonstic unit. GM does very extensive field proving of the ECM. Once the unit has been thoroughly tested off road on GM's test track, the four people on the coding team serve as guinea pigs for the ECMs. They use Citations with Motorola diskless development systems in the back seat. The development system is wired to a `heads-up display' that is velcroed to the dashboard. The display has toggle and rotary switches that that allow the driver to select from a number of advance curves, etc that are under consideration. It was quite amusing, as I got to drive with a guy in a Citation that could blow away almost anything else on the road. The only problem was that its tires really weren't up to the power capability of the engine. They were really amazed to have an interviewee that could say phrases like "top dead center" and "mass air flow sensor", let alone know what they meant. I didn't take the job because the arrangement of working through the headhunter was pretty sleazy. I've thought about trying to go back and get a job there directly though GM, as it looked like a pretty neat place to work. In summary, I don't think it would be a real good idea to try to hotrod the ECM yourself. If you did something wrong, you might get into a situation where you developed uncontrollable acceleration or some nasy situation (the idle stop on some engines is controlled by an electric motor). To me it looks like the design work behind the ECM is pretty thorough, and you probably couldn't do too much to tweak the engine for performance. The ECMs do, however, have a maximum speed of 85 MPH. I have a friend that works for Goodyear that exlained that. The FBI was outfitting some Chevy Caprices for high speed tires and came across that fact. They had to go back to GM to get some cutsom ROMs burned that would let the cars go faster. Tney needed to do that so they could catch people with older analog cars or imports (grin). --Bill
piner@pur-phy.UUCP (Richard Piner) (05/13/87)
In article <581@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes: > > The ECMs do, >however, have a maximum speed of 85 MPH. I have a friend that >works for Goodyear that exlained that. The FBI was outfitting some >Chevy Caprices for high speed tires and came across that fact. >They had to go back to GM to get some cutsom ROMs burned that would >let the cars go faster. Tney needed to do that so they could catch >people with older analog cars or imports (grin). > Gee, they must have let one of those ROMs slip through. Just to see what she would do, I opened up my new '86 Cavalier and the needle went right past 85. The speedometer will go past that, but there are no numbers to read. In fact, the speedometer reads neagtive when backing up. Anyway, she was still accelerating around 90-95 when I backed off. God must have been smiling on me, because after I slowed down to 55, I passed THREE speed traps in the space of a mile. Richard Piner piner@pur-phy.UUCP
hedley@cbmvax.UUCP (05/13/87)
>lots of yapping about shitty dealer service.
I used to agree with this, but I moved to new place, bought a
new car ( 3 years ago ), and have found, much to my surprise that
the dealer really has a compentent service staff. The only problem is
that they are so damn busy that its hard to schedualed, but they take
good care of you, and seem to do the job right the first time ( well,
most of the time any way. :-) ).
They're in West Chester , PA, called James Chevrolet.
( On the other hand, I could pooh-pooh a couple of other chevy
in the area. )
Hedley