'7747 r.i.p.

[dave w]

I upgraded a '7747 ECM to a '427 PCM. The Vehicle is a 1987 GMC 1 Ton 454. I am using $OE definition file (1995 454 MT). I spent about 8 hours, including the PROM programming to complete the conversion. I still need to "Dial In" the PROM. The '427 will operate the 4L80E (to be installed at a future date).

Here are the notes I found / copied from Thridgen.org about doing the upgrade, I added some notes also.

dave w

Notes and information on converting to a TBI PCM
I have had multiple people ask about re-pinning their earlier TBI cars/trucks
to use the latest PCM. So here is the result. Information regarding the swap.
PCM Swap/Tuning Notes
8746/6965/7747/299 to 427 Truck PCM (Car showed, Trucks VERY similar)
Old Pin----New Pin-----Color------------Function
A1--------F6----------GRN/WHT-------Fuel Pump Relay Control
A3--------F16---------DK GRN/YEL-----Charcoal Canister Purge Solenoid *** Not used on 87 GMC W/454***
A4--------E1----------GRY-------------EGR Control
A5--------E6----------BRN/WHT--------Service Engine Soon Light
A6--------E15---------PNK/BLK---------Ignition Feed +12VDC
A7--------(1*)--------TAN/BLK---------TCC/Shift Light *** Investigate***
A8--------F9----------ORN------------Serial Datastream
A9--------A14---------WHT/BLK-------Diagnostic Test
A10-------F13---------BRN------------Vehicle Speed Signal ***Output Speed not from DRAC set***
A11-------B3----------BLK------------Sensor Ground
A12-------A1----------BLK/WHT-------ECM Ground 1
B1--------E16---------ORN------------Battery +12VDC
B2--------B12---------TAN/WHT-------Fuel Pump Signal
B3--------A5----------BLK/RED--------EST Ref Low
B5--------A4----------PPL/WHT-------EST Ref High
B6--------?-----------PPL-------------VATS(2*) *** Not used on 87 GMC W/454***
B7--------(3*)---------BLK-------------Knock Sensor *** Not used on 87 GMC W/454***
B8--------E12---------LT BLUE--------A/C Clutch Signal ***GRN Not LT BLUE 87 GMC W/454***
B10-------E5----------ORN/BLK--------Park/Neutral Switch ***Investigate***
C1--------(4*)-------BLK/PNK---------A.I.R. Converter Solenoid *** Not used on 87 GMC W/454***
C2--------E7---------BRN-------------A.I.R. Port Solenoid (Diverter in trucks) ***Investigate***
C3--------A7---------LT GRN/BLK------IAC "B" Low ***LT GRN-BLK on 87 GMC W/454*** --- A7 1995 7.4
C4--------A8---------LT GRN/WHT-----IAC "B" High ***C4 WHT EST SIGNAL on 87 GMC W/454*** F11 1995 7.4
C5--------A3---------LT BLU/WHT-----IAC "A" High ***C5 LT GRN-WHT on 87 GMC W/454*** --- A8 1995 7.4
C6--------A6---------LT BLU/BLK------IAC "A" Low ***C6 LT BLU-WHT 87 GMC W/454*** --- A3 1995 7.4
C7--------(5*)-------LT BLU-----------High Gear Switch (In Auto Trans) ***C7 LT BLU-BLK on 87 GMC W/454*** --- A6 1995 7.4
C8--------(6*)-------LT BLU-----------Power Steering Pressure Switch ***Not used on 87 GMC W/454***
C9--------(7*)-------PPL/WHT---------Crank Signal
C10-------B8---------YEL--------------Coolant Temperature Signal
C11-------B13--------LT GRN----------MAP Signal
C12-------B9---------Tan-------------MAT Signal(8*) *** Not used on 87 GMC W/454***
C13-------A15--------DK BLUE--------TPS Signal
C14-------E14--------GRY------------5 Volt Reference
C15/D14--A9---------DRK GRN--------Injector "2" Control *** D14 on 87 GMC W/454***
C16------E13--------Orange----------Battery (Inputed in place of Brake Switch
for TCC to function)
D1-------A2---------BLK/WHT--------ECM Ground 2 *** TAN-WHT on 87 GMC W/454***
D2-------B4---------PPL-------------MAP Sensor Ground
D4-------F11--------WHT------------EST Signal
D5-------B2---------TAN/BLK--------EST Bypass
D6-------A12--------TAN------------O2 Sensor Ground
D7-------A10--------PPL-------------02 Sensor Signal
D15/D16--A16-------DK BLUE---------Injector "1" Control ***D16 on 87 GMC W/454***
Swap Notes
*** Throttle Kicker Enable disabled***
*** Initiate Integral with Calibration Const. Not Running enabled ***
(1*)= Use E2 for a shift light on a manual transmission or E10 for the TCC on
an Automatic
(2*)= Supported by the PCM if optioned in the Prom on an UNKNOWN pin
(3*)= A.) Wire like 1995 P30 Step Van, ESC Module output to B7
(3*)= B.) Wire like 1995 C10 Truck, Bypass ESC (Blue to Brown) and use
Late TBI/TPI 305/350 Knock sensor
(4*)= Air injection into converter not used on trucks, but PCM has several
other un-used outputs (Tuning Valve, Idle Kicker)
(5*)= Not Used by PCM (I like to leave the small connector in place and pin
in unused wires)
(6*)= Supported by PCM if optioned in the Prom on an UNKNOWN pin
(1994-1995 2.2 S10 Wiring Diagram anyone?)
(7*)= Not used by PCM, Remove 3 amp "CRANK" fuse from fuse box and
store in small connector)
(8*)= Supported by the PCM, but functionality will need to be enabled in the
Prom
6965 ONLY- Will have a NC relay that the computer grounds to shut-off the
A/C compressor when the engine is heavily loaded. The A/C will work either
by removing the wire all-togather, or connecting it to pin E3 (A/C Cut-Off or
CPI Tuning Valve output)
I would also like to mention that the orange Serial Data wire needs to be
relocated from the top row, Pin "E" to the lower row, Pin "M". You will also
need to scan the vehicle like a 1993-1995 G-Series Van, C-Series Truck,
S-Series Blazer, etc with Auto transmission.
Finally, this is a trick Haulin@$$ taught me, if you have a wideband and are
looking to get real-time AFR put into the datastream, hook the 0-5 volt signal
into pin B16 (Linear EGR pintle position feedback). With some adaption to the
ALDL Definition being used to decode the reading, you can get an AFR
reading of 10-20:1 or so.
__________________
350 Vortec shortblock, balanced, blueprinted, 18cc dished pistons, total seal
rings, ported 906 Vortecs, Edelbrock TPI Vortec base, Custom Reed Grind
Hydraulic Roller Cam, Doug Thorley Tri-Ys, 2 1/2" exhaust, Stock TPI runners
and plenum, stock 48mm TB, 24# LT1 injectors, AFPR @ 46 psi, 7730 ECM,
DIY Tuning, stock 1,600 rpm stalled 700r4, 3.08 gears, P295/50/R17 tires.
Soon- 4L60E and 7427 TBI PCM in MPFI mode

 

[eagle mark]

so what was your goal with this conversion? Just the trans? Or were you looking at the faster computer?

 

[dave w]

so what was your goal with this conversion? Just the trans? Or were you looking at the faster computer?

Both, getting the faster computer allows using DataMaster data logging software. Upgrading to a 4L80E is the next step.

dave w

 

[Keitha]

Did you ever consider using the 16147060 PCM w/ an $85 definition file? I'm just curious what the advantage is with the 7427? I have a 16147060 in my Sub and find that it is a bit difficult to get a good XDF file to log and tune with. I pulled the only one from Moats, and it is OK, but to totally comprehensive.

 

[dave w]

Did you ever consider using the 16147060 PCM w/ an $85 definition file?.

No, not really. My 1993 GMC uses $E6 .xdf and the '7427 uses a very similar $OE .xdf. I liked the ability to use similar code. I am able to use my bought and paid for $E6 DataMaster tuning software with the $OE. So there was nothing extra needed for me to buy for the "tuning tool box"

I'm just curious what the advantage is with the 7427? .

I found tons and tons of accurate and useful information on the '7427 conversion on Thridgen.org and other websites. For me, the advantage was good tech info, faster computer, able to upgrade to a 4L80E (still working on that upgrade), use tuning software I already have, and very low cost for the PCM. I spent less than $100, and that includes the PCM with memory adapter I purchased from Moate.net.

I have a 16147060 in my Sub and find that it is a bit difficult to get a good XDF file to log and tune with. I pulled the only one from Moats, and it is OK, but to totally comprehensive.

I say "use what you know!"

dave w

 

[Keitha]

I am sticking with the 16147060 PCM as it works well and is stock with the 3/4 ton 1991 Sub w/ 4L80e. I just am curious about the one you are using. I did a bit of reasearch and it seems like there is a ton more data on the 7427 (not too many people have messed w/ the 7060 for some reason).

Thanks and best to you,

 

[bronc3buster842001]

Ok I used the '427 ecm to put a 350 in a 95 s10 blazer. The tranny will not shift at all. We get codes 43, 55,and 59. $3 is for the knock sensor. From the info I have seen 55 is an ecm error. 59 is the TFT sensor. I am at a loss as I am new to this kinda stuff. Thanks.

 

[dave w]

Ok I used the '427 ecm to put a 350 in a 95 s10 blazer. The tranny will not shift at all. We get codes 43, 55,and 59. $3 is for the knock sensor. From the info I have seen 55 is an ecm error. 59 is the TFT sensor. I am at a loss as I am new to this kinda stuff. Thanks.

From what I can figure out, the 95 S10 Blazer most likely had a TBI 4.3 V6 / 4L60E as original equipment?? From what I can figure out, all that would be needed to convert from the TBI 4.3 V6 to a TBI 5.7 would be a custom programmed V8 PROM chip for the 5.7 engine. I don't think using a V6 PROM chip for a V8 will work??

Maybe what has happened is the 95 S10 Blazer was reconstructed with a mix of parts that requires an enormous amount of homework / labor to get everything working??

dave w

 

[bronc3buster842001]

It had the vortec v6 with the black box ecm.. We put in a 350 tbi. Redid the wiring harness to use the 427 pcm. The pcm come from a v-8 truck.

 

[dave w]

It had the vortec v6 with the black box ecm.. We put in a 350 tbi. Redid the wiring harness to use the 427 pcm. The pcm come from a v-8 truck.

Where did the wiring diagrams come from that you used? I used both the 1987 GMC and 1995 GMC wiring diagrams. I also used wiring information form Thridgen.org. Before I started the truck, I triple checked each wire. I actually found that I had swapped two wires ... I guess that makes me human

dave w

 

[bronc3buster842001]

I used the wiring diagram from a 95 blazer as they had either the tbi or vortec motor that year. got the diagrams from mitchell on demand.



EDIT.... Got the tranny to shift. I was trying to use a drac box instead of the vss box. They look identical and and it never dawned on me. Then it came to like a light bulb. Still getting a code 59 and and now a code 54.

 

[dave w]

Here is what I found searching the net on code 55. http://www.freeautomechanic.com/diagnostictroblecodes5.html

dave w

CODE 55

Trouble Code 55 indicates that the Analog-to-Digital (A/D) converter in the ECM is faulty. This converter reads sensors (e.g., TPS, Oxygen) and coverts their analog voltage output to a digital number for use by the ECM. If the converter fails, the ECM sets this code.​

The conditions for setting this code are:​

• the A/D Converter has failed to properly read a sensor after 24 attempts.

Typical causes for this code include:​

1) Defective or incorrectly inserted PROM
2) Defective ECM​

If replacing the ECM, be sure to transfer both the PROM and the CALPACK from the old unit. If the old ECM also indicated PROM failure (Code 51) or a bad CALPACK (Code 52), be sure to verify these components are fully operational in the new unit. If they are not, they too will have to be replaced.​