I have been spending my odd time on my 3800 sunfire swap and have a few questions. The donor is a 1996 olds 88 and the recipient is a 2002 sunfire.
The 3800 series 2 and 4t60 are both going into the sunfire.
I have been pouring over this forum and others all winter and have also been studying the wiring diagrams. I see that some people have problems running their gauges on the donor pcm.
How do I know if this will be a problem for me? The wiring looks pretty straight forward and I think I should be able to just splice into the body harness and call it good.

This swap will be a daily driver.

I forgot to mention, there won't be any A/C, but I do plan on using the cruise, but there is no cruise switch on the sunfire. I would be ok with using buttons.

Supercharged or non-aspirated?

For N/A you could use a 2000-04 Impala/Supercharged 3800 PCM to run the gauges
For Supercharged you could use a 2004 Impala SS/Monte Carlo SS PCM

Both would require some mild rewiring and possibly a few sensor changes, and I'm not sure if they would shift the 4T60E properly.

OR you have to use custom gauges OR piggyback your Sunfire PCM into the harness OR rewire the entire car as a 96' Olds 88 and use the Olds gauges.

It is N/A

So the olds pcm will NOT run the gauges?

Will the stock fuel pump run the 3800 or do I need to swap stuff around? Will the pump from the olds fit the sunfire or do I need to put the whole sending unit in?

read the sticky bud cause its there and has been discussed. Na your wasting your time. ecotec cars will be kicking your a$$ at the track with an NA

also the fuel pump on an NA is fine from a sunfire the fuel pump will work on a stock SC engine too.

BEFORE YOU START THIS GO BACK TO THE STICKY AND READ IT CAUSE YOU NEED TOO, YOUR NOT READY TO DO THIS SWAP YET



JBO since July 30, 2001

The problem I am having is that people are saying "get this computer for this combo", but I have something different.
I can piggyback the sunfire computer for the gauges if I need to, otherwise I can use the olds cluster. It doesn't matter to me.
I guess I will stick with the sunfire pump and see what happens. I will save the olds pump in case I need it.
What about the chime module? Can I take it out or does it have to stay?

I don't care about times, this is a daily driver.

get the right computer it will cost you more money to use the olds computer if its not the right service number then it will to buy the right one there 50 bucks at the wrecker sounds like your doin a BIG swap on a tight budget you can do an eco for less and it will be faster

olds pump wont help either get a racetronix pump if you need more but you wont but you seem to know more then me so do what you want.

doin an engine swap has nothing to do with chimes bud i would seriously research this future and seeing as you started a thread and not post in the one that stickied leads me to think your sifting through info



JBO since July 30, 2001

Listen to NOTa2_4 he has accomplished this swap and has answered many questions about the swap.... If you cant stand expert criticizing then why didn't you just post the questions under the swap sticky.... Also if i remember correctly not saying i do but the cradle would have to be measured, cut and welded to the spec of the cavalier so unless you have access to a machine shop and a welder the swap is very expensive.... Also maybe its just me but it seems like you doing a lot of swapping for a daily driver.... If its just a daily why not just put the right engine in it??? It would be more cost effective....


Erik Packard

All I wanted was a straight answer to my questions. The subframe is already taken care of, and I am NOT worried about how fast it is.
I am using the 3800 because it is a custom build and I already have it. There is a lot of sentimental value in it for me.
My grandma had the motor built when I was a kid, so I am not getting rid of it. I would rather put it in a car and run it, than put it in a back corner.
All I need to figure out is a few small points on wiring. If nobody here can give me a straight answer then so be it, I will just figure it out myself.

For a nice straight answer about using your stock gauges:

Nic Crosby wrote:For N/A you could use a 2000-04 Impala/Supercharged 3800 PCM to run the gauges
For Supercharged you could use a 2004 Impala SS/Monte Carlo SS PCM

Both would require some mild rewiring and possibly a few sensor changes, and I'm not sure if they would shift the 4T60E properly.

OR you have to use custom gauges OR piggyback your Sunfire PCM into the harness OR rewire the entire car as a 96' Olds 88 and use the Olds gauges.

This was posted in the thread and gives the exact answer you were looking for. NOTa2_4 is just trying to make sure that you can get this done. I have read teh sticky for the 3800 swap, and the answers you are seeking are in there as well. I highly suggest that you read it all the way from the beginning and then, if there are still questions ask in that thread. That way all of the people that are subscribed to it can give you answers and help you out as well.

the reason you can't use the olds pcm for your cluster is the way the olds sends signals its the same reason you can't use a grand prix pcm wiring wise you just have to move 4 wires i know this cause i have built a few harnesses and the one in my car is a 6th revision. and to be exact its a 01 grand prix 3800 NA harness that has been repinned as an 04 impala 3800SC its so easy to do you just need to get the fact that the cost of making the olds PCM work on your car will in the end cost you more money to do then goin to the wrecker and getting the right one.

you would have to piggy back your PCM and the olds PCM thats 2 pcms and 2 sets of wires to do the job of 1 pcm and 1 set of wires and if you can't figure out what wires need to be move your gonna have a hard time piggy backing it
not to mention 00+ is so easy because of the impala PCM you need service number 12583827 its used on 03-05 montecarlos, impala, malibu, century, regal, grand am like its such an easy PCM to get but if you get one from an impala with at 3800 you wont need the dealer to flash it



JBO since July 30, 2001

Thank you for explaining WHY it won't work. That is the info I was looking for.

most just listen when we say it wont we've been around and tried things year before most of you got licenses



JBO since July 30, 2001

I've been around a while too. I have learned to take everything with a grain of salt. I've been told too many times that stuff will or won't work when in fact it actually worked.
I am going to pull the cluster out of the sunfire and see if I can bypass the microprocessor and run the gauges directly. The cluster runs on the UART data line to save wiring, but the gauges themselves should run on the same signal as the olds gauges. I might have to do some soldering/wiring, but I want to see if this works. If it doesn't work, I will use the cluster out of the olds. I just want the tach.....
I like putzing around a little, so this will be like therapy for me. I will be labeling the wiring harnesses today and tearing the interior out of the sunfire so I can get to the wiring. The good news is that the sunfire is easier to tear out than the olds. WOW that olds was a job. I have to fix the heater fan on the sunfire and a few other items, so this is the perfect time. I might even put the olds blower in there if it will fit. Then I can get more hot air. The sunfire blower is kind of wimpy. The A/C is removed, so that gives me some room to rearrange thing under the dash and maybe put some bigger plumbing in there.
I might even put a rear heater vent in! WOO HOO!!! I am even toying with the idea of putting the sterio system from the olds in the sunfire. I just can't throw away a nice setup like that. The sunfire had the worst radio ever. EUCH!

serious dude do what you want cause your gonna anyway why post questions if you don't want the answers. first of all your olds is a 96 and the fuel level reads 0-90 ohms and 99+ is 40-250 so there one thing that wont work right your sending unit will be at 40ohms and the gauge would read 1/2 tanks when you are accually empty unless its a direct feed from the sender i for get what years did that.

you will have BCM communication issues since the cluster comunicates through the BCM as does the PCM the only physical way around this is to re wires your car as an 98 or older and if you (probably will) do this its more work then getting the right PCM. also the sunfire radio is a better radio then the 96 olds radio also olds radio is a 1.5 DIn not a 2 din radio so theres modding for that then is also not a class 2 device and there wire modding for that but you know then me and since your attached to is you should just sell the sunfire and drive the olds 88 you will have less tickets a younger people don't drive them and cops wont ecpect a young guy in it.

your best to stop posting here for advise because you don't want the truth you want us to tell you what you wanna hear and a number of the serior guys that have gone indepth on these swaps have messaged me about this thread, JUST SO YOU KNOW DO WHAT YOU WANT WE WONT HELP YOU FIX IT, WILL JUST I HATE TO SAY I TOLD YOU SO BUT WE TOLD YOU SO.

trying to give you the simple cleanest easiest way to do it but you wanna do it the hard way . just so you know the horse goes infront of the cart



JBO since July 30, 2001

sorry for the lact of commas but you get the point anyway




JBO since July 30, 2001

I swapped the radio last night. It was a direct fit.

The fuel sender is a 40-250, so that will work fine.

The olds is rusted out underneath. That is why I pulled the motor in the first place.

Just how much do you know about these swaps, because you have contradicted almost everything in your sticky.
Senior guys? I hear a bunch of 18 year olds talking.

I'm going to chime in here, because although I applaud your willingness to try something different, and not give up just because you've been told it won't work (I can empathize with this...the best way to get me to do something is to tell me I can't. LOL), I do have some insight to offer you regarding your ideas:

Isaac Carlson wrote:...I am going to pull the cluster out of the sunfire and see if I can bypass the microprocessor and run the gauges directly. The cluster runs on the UART data line to save wiring, but the gauges themselves should run on the same signal as the olds gauges. I might have to do some soldering/wiring, but I want to see if this works. If it doesn't work, I will use the cluster out of the olds. I just want the tach.....

The UART signals are different between the two vehicles. Although they use the same protocols, the location in the datastream varies by vehicle. GM is annoying like that. There has not yet been a 3100, 3400, or 3800 ECM flash found yet that will run the 95-99 J-body gauges properly. I've actually compared the datastream description files for over a hundred vehicles, and have yet to find one that matches those year J-body signals.

The gauges are run off 4 pole stepper motors that use perpendicular magnetic fields to align the needle according to a sine/cosine trigonomic value given them by the microprocessor. In order to do what you want, you need to run the motherboard from the cluster of a donor vehicle, and run wires to the motors of the J-body needles. It can be done, but it's not pretty.

What I'm still slowly working on for swap guys is finding the hex mask required to locate the serial data description file in the ECM's program. This differs on almost every ECM, so it's a royal b!tch, and mostly time consuming. Once I am able to find the location, I have the file descriptions for a ton of GM later model vehicles, from mid 80-'s to early 2000's. I should be able to manually edit a .bin file and replace the serial data description, allowing the ECM to be reprogrammed to run the necessary cluster. Again, it's a time-consuming, and PITA of a process, but I enjoy the challenge.

Another option for you, that I've been hoping to see someone try, is to use the ECM, wiring harness, and gauge cluster from a 99-04 Buick Regal. The cluster is similar in size and shape to the J-body clusters, and the Regal was available in the 3100 and 3800N/A engines.






Edited 2 time(s). Last edited Thursday, April 18, 2013 9:17 AM

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18 my a$$ chump try almost 30
as for senders your sunfire is 40-250 your olds is 0-90
your radio in the olds is a 1.5 DIN and 00+ radios are 2 din or double din sorry bud these are facts

my 12 years of being on these boards to you 1 yeah. just bud remember this IF YOU WANT HELP LISTEN, DON'T TELL.

did your grandpa rebuild the PCM too is that why you have such an attachment to it. either way you look at this your getting HPT on that thing so 96 without VATS verse 04 with VATS is minor you will need to shut off a few codes but its all yours engine your HEAVY a$$ 200hp tank



JBO since July 30, 2001

LOL Matt. You gotta relax a little. You are taking this too personally. If he wants a boat anchor for his car, let him put a boat anchor in it. Your car will still be faster.

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I don't care how fast it is, it's not for racing. If I cared about that, I wouldn't have a 2.84 final in it

I checked the resistance on the olds sender just to see if the specs were right, and it was 0-90. Don't flame, every replacement sender I could find/look up was 40-250.
I was going by the parts list until my brother could bring the meter back.

The radio is a direct fit. There is no wireless or computer screen or anything on either one. It has a plug for the olds harness and the same antenna plug.

If I use the olds sender, cluster, harness, pcm, radio, etc, exactly what would keep the swap from working and why?

shawn my car isn't very fast its melted down by now, all the parts were removed and are in a new car from northbay no idea what i will work on next GTO or CTS-V possibly



JBO since July 30, 2001

Matt, do yourself a favor and turn away, you will live longer!

Whats a 3800?