I believe it’s a chip swap.

 

It is a chip swap. There is a small door with 2 screws. Make sure your old and new ones the service number matches. There were some variants depending on exact model and options.

 

What if the numbers don’t match?

 

Not sure where you are buying your new one. If it is one of the better parts store or dealer most will help you change chips.

 

Or it could be a simple broken wire or bad ground. Have you checked every wire in the ignition system at both ends for continuity.
Word of advice when changing anything electrical, but especially ECM's. Disconnect the battery before you do anything.

 

I always disconnect the battery, I’ve seen people cost themselves money just trying to do simple cheap stuff. I haven’t checked both ends of every ignition system wire because I couldn’t find any diagrams for the truck and wasn’t sure where everything went. I have checked the battery and the connectors for the distributor and ignition coil and a few others that I can’t remember right now.

 

Not trying to be a smarta**, have you verified the rotor in the distributor is turning when you engage the starter? Could be a stripped timing gear as i recall that 2.5 had a fiber cam gear. Just throwing out ideas.

 

I actually haven’t, somehow that slipped my mind and I never even thought of it. I will check that today and I plan on getting my old computer and taking it with me so I can see if the numbers match, I ordered from Oreillys and they never mentioned having more than one variety so idk.

 

I forgot to mention but my fuel injector is not spraying either and I was told that the computer controls the spark and fuel injector which is another reason I was leaning towards replacing the ecm. The fuel injector is clean and has voltage and I am getting fuel to the injector so I know fuel pump is good. Does that sound like a bad ecm at all?

 

 

would looks something like that. It is the spark control module.

 

I don’t recall seeing that anywhere, that oooks like a more square version of the module inside of the distributor?

 

if you are looking at the firewall it is slightly to the passangers side center and up close to the flange of the heater / ac box

 

edit: your truck my not have it based on its age.

 

Okay my truck does not have one. It has a diamond shaped piece that looks like a grounding location in the location you described.

 

just checking to make sure something obvious was not missed

 

Just out of curiosity what would happen if the ecm and prom were different? Would I just get nothing or would there be big issues or could it just be programmed?

 

The prom has to stay with the truck. It contains all the info the ECM needs for your particular engine, transmission, etc.
ECM's rarely fail. Not saying it can't be, but I'd bet 90% of the ones replaced didn't need to be. Something else was the problem. If the numbers don't match at O'reillys don't be too concerned as long as the electrical connectors are exactly the same and the Prom will switch. In that era GM used different part numbers on ECMs that were basically the same. Usually, if a newer faster or better computer was introduced during a model year they would just change to it. In later years they only did it when the MY changed. And then they changed almost every year.

 

So as long as the prom plugs in I’m good? Oreillys said they will accept returns on the ecm if it’s not the problem

 

I got the computer today and my eprom doesn’t fit, my eprom is the long skinny type and the new computer took the short square shaped one. Got another one on the way. I’m at the only other one Oreillys carried so hopefully it works

 

If you have the service number I may have a spare i am happy to send for just shipping. I have collect a few over the years for various projects and experiments. Of take some pics and post here.

 

Not sure if the 2.5 back then had a crank sensor. If it has one was the crank sensor checked at all? no RPM signal results in no fuel/no spark.

 

 

that is the oldest one i have in my stash pay no attention to the chicken scratches on it other that it is from a 1988

 

That is similar to the one I got that was wrong. My service number is 1227165.

 

Cool on the clarify. Just trying to throw you a lifeline if needed

 

Is the check engine light on with key on ? Are there any codes? I worked at Chevy dealer form 1983-2007 and can only remember replacing a couple of ecms on these trucks

 

I have a battery light and a shift light on that’s it

 

Can you flash codes?

 

Not positive what you mean by that.

 

A 16198259 will replace your 1227165 and is better computer.

 

A 16198259 will replace your 1227165 and is better computer.

Thank you, where do I get that part? Online or is it specific to a certain part store. Also is it better because of build quality or the boards inside?

 

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If you don't have a check engine light with key on engine off, you might not have proper power or ground to the ecm.

 

What grounds or wires should I be looking for to check this and would a bad battery cause this?

 

You would need a wiring diagram or at least a pinout for the computer. A lot of ecms ground to the cylinder head at the rear of the engine.

 

Would you know where I could find one of those? I’ve looked for diagrams and can’t find anything reliable. I have a ground from firewall to the rear of the engine and I have the negative battery cable to block and a ground from the negative cable to the inner passenger fender I think that’s all of my grounds

 

gotta have the chip set!!! memcal is where all the data is loaded to in those old ECM's. you need a scan tool to see if you have a crank signal.

 

My understanding is that the chip will just swap directly to the new computer and is already set?

 

Check the 10 amp ECM fuse. Diagnose as No power to ECM.
I think this is close enough to work for your 1987
1988 Chevy Chevrolet S-10 TRUCK Electrical Diagnosis Service Manual Supplement