Bad running after manual swap

[1998_K1500_Sub]

Ok thank you. I did keep my automatic computer, I wonder if this is the problem.

For my 94 truck, which year of computers will work? If its like a from like a 93 or 92 would it still work? Also does the engine have to be the same in the donor truck?

Asking because my local junkyard has a manual truck(the same truck I got my pedals and shifter from) but I'm not sure exactly what year it is. Definitely a 92-94 though.

Probably just a different "chip" (MEMCAL / CALPAK / whatever) is what's required, retaining the same computer... "probably". In the '94-'95 years, the ECU p/n 16197427 was common.

There will be wiring changes too, perhaps modest. Get the FSM and take a look there.

 

[fancyTBI]

Ok thank you. I did keep my automatic computer, I wonder if this is the problem.

For my 94 truck, which year of computers will work? If its like a from like a 93 or 92 would it still work? Also does the engine have to be the same in the donor truck?

Asking because my local junkyard has a manual truck(the same truck I got my pedals and shifter from) but I'm not sure exactly what year it is. Definitely a 92-94 though.

You should try to get a ‘94.

 

[JPVortex]

Ok thank you guys!

 

[JPVortex]

Probably just a different "chip" (MEMCAL / CALPAK / whatever) is what's required, retaining the same computer... "probably". In the '94-'95 years, the ECU p/n 16197427 was common.

There will be wiring changes too, perhaps modest. Get the FSM and take a look there.

Well I’m unlucky, my PCM number is 16196395.

 

[JPVortex]

Well I’m unlucky, my PCM number is 16196395.

seems like 16196395 and 16197427 are very similar PCMs. They both run $OD, so in my case should be interchangeable from a manual truck.

 

[JPVortex]

So I went down the rabbit hole with this PCM thing. I know it has to be from a 94 or a 95. But I’m confused with how many different part numbers there are. Will any 32 pin PCM from a 94-95 manual truck fit into my truck?

Also if the pin outs are different can I just stick the PROM from the manual one into my PCM?

 

[1998_K1500_Sub]

So I went down the rabbit hole with this PCM thing. I know it has to be from a 94 or a 95. But I’m confused with how many different part numbers there are. Will any 32 pin PCM from a 94-95 manual truck fit into my truck?

Also if the pin outs are different can I just stick the PROM from the manual one into my PCM?

Cupla' things...

You'll likely only need something like this:

You must be registered for see images attach

There's a four-letter code on it, and you'll want to find one that's appropriate. If you get one from a junkyard truck that has a similar ECU, you can probably be certain it's appropriate. There are tools out there (more on that in the next post) that allow one to take that four-letter code and "decode" it to determine the application for which the MEMCAL was intended. That tool is available on TunerCat's website.

Supposedly "The 6395 pcm part number is replaced by the 7427 pcm" and they're interchangeable. I can't confirm this from personal experience; maybe someone else can. I do know from personal experience that three different 1995 trucks in my family used the 7427 PCM, so it may well be the "later" incarnation of the same ECU functionality.

The pin assignments will be different for the different applications, manual or auto (e.g., the manual ECU triggers the "upshift" light in the cluster IIRC). The pin assignments are almost certainly "soft" assignments, i.e,. determined by the firmware. So, plugging the MEMCAL from the manual into your ECU should result in something functional... although perhaps in need of wiring changes to make it whole.

I would look in the service manual to see what the difference is in the pin assignments / wiring. It may be the differences are somewhat trivial, and thus allow you to run the manual MEMCAL with the automatic wiring w/o change... although you might want to modify the wiring eventually to enable some missing feature. I would expect all (or almost all) engine control functions to use the same wiring. Ditto for the AC (although there may be subtle differences). Obviously, the pins used for the auto trans control might be re-assigned to different functions in the manual truck. Too, don't be allow yourself to be confused by the possibility that an ECU pin might be used as an output in the auto truck but be used as an input in the manual truck, or vice versa.

I hope this helps.

Oh, one other thing. Sometime in '95 GM started deploying the "OBD1.5" systems, which employed an ECU under the hood instead of in the cab, and of course a different wiring harness and an incompatible firmware load (meaning, it's not $0D like the earlier ECUs) which was AFAIK not able to be modified. This one is not one you'll want to use in this retrofit; don't let someone sell you one / don't even think about trying to retrofit one.

 

[1998_K1500_Sub]

(cont'd)

I see TunerCat's site says this about $0D

$0D 16196395 or 16197427
94 - 95 C/K Truck, Van, S-10 LN2 (16168505), 4.3L, 5.7L & 7.4L

See http://www.tunercat.com/tnr_desc/ecm_sup.html

Their CALDATA application will decode the four-character broadcast code and tell you about the intended application.

See http://www.tunercat.com/caldata_desc/caldata_desc.html

Finally, you'll see that a variety of firmware loads may apply to your application; $0D was used, as was $8C (at least in the automatics). I've used both $0D and $8C. You may stumble upon either, or others, in your journey. As long as the firmware was designed to run on your platform (see Tunercat's link above for ECU support), you should be OK.

I'm not the last word in tuning / ECU swaps by any means. Hopefully others here will comment. I suspect @PlayingWithTBI might have some input.

 

[JPVortex]

(cont'd)

I see TunerCat's site says this about $0D

$0D 16196395 or 16197427
94 - 95 C/K Truck, Van, S-10 LN2 (16168505), 4.3L, 5.7L & 7.4L

See http://www.tunercat.com/tnr_desc/ecm_sup.html

Their CALDATA application will decode the four-character broadcast code and tell you about the intended application.

See http://www.tunercat.com/caldata_desc/caldata_desc.html

Finally, you'll see that a variety of firmware loads may apply to your application; $0D was used, as was $8C (at least in the automatics). I've used both $0D and $8C. You may stumble upon either, or others, in your journey. As long as the firmware was designed to run on your platform (see Tunercat's link above for ECU support), you should be OK.

I'm not the last word in tuning / ECU swaps by any means. Hopefully others here will comment. I suspect @PlayingWithTBI might have some input.

Awesome, thank you so much for all this information! This does greatly help.

 

[JPVortex]

So just an update here, went to the junkyard and failed to find anything that’d work.

Both the manual trucks PCMs here had a different pin out then my trucks PCM, and the prom chips were also the older style smaller ones.

I think my only bet now is to get a custom made chip. Was looking at harristuning.com. They’re pricey but it may be my only option.