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Converting a 5SFE Harness for MSPNP on a 3SGTE

Thu Mar 08, 2018 4:17 am

...or at least attempting to.

This is specific to the 92-93 years of the ST185.

I wanted to start a new thread because my questions on the ig1 and ig2 have been answered.

The reason I'm doing this is because I've eliminated a lot of the extra stuff in the engine bay like the EGR and EVAP systems, cruise control,fuel pump and injector resistors, ac idle up, ignitor, ignition coil, TVIS, and AFM. I'm also going with Toyota Prius 1nz COPs( I know I should have gone 1zz but I find it entertaining to use Prius parts).

I've also added things like a GM intake air temperature sensor and an electronic boost controller that's controlled by the mspnp. I also have a side feed intake manifold from an 89 gt-s, a fuel rail from an 87 celica, 850 cc denso injectors with different plugs, and a FMIC, and a supra TT fuel pump. None of which is installed yet.

Still undecided on bolt on turbo but the ATS ct-27 is in the lead. I'm not looking for huge horsepower since this is only a street car.

I also stumbled upon some undocumented features of the mspnp concerning the 26 pin DBA plug which I will cover later.

The other reason I'm doing this is I don't like unnecessarily chopping up my original wiring harness which is rather rare and valuable. There may be a time in the future where my car is more valuable returned back to stock condition than the modifications I make to it.

I also wanted to document my attempt at converting a wiring harness from a 1992 Celica automatic 2.2. It must be from an automatic because the plugs on the m/t 5sfe are wrong.

Now on with the show...
3SGTE Pinout for 1992 Celica

5SFE Pinout for 1992 Celica Automatic

* as I was typing this out and looking through the ewd book I discovered some inconsistencies. The 3sgte has the plugs labeled B C A from left to right. The 5sfe is listed as A C B. For the purpose of typing this out, I'll be using the 3sgte perspective.

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Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Thu Mar 08, 2018 4:21 am

ECU Plug B

The first plug I'm going to cover is ECU plug B. It's the first one on the left when you look at it from the back of the ECU, it has 26 pins in it.

The first things of interest to me is the 5sfe only has 2 injector outputs so the batch fire injector wires need to be removed.

Second thing of interest is, this is where a lot of A/T wiring is so all that needs to be removed.

3rd thing of interest is the distributor wiring. The 5sfe signal wires appear to be of a thinner guage, 20 or 22. The 3sgte looks to be 18 or 20. The colors are correct at the ecu, but need to be moved on the plug to the dizzy. This should be fine to use since the dizzy is now nothing more than a cam/crank sensor to me. It looks like Red and Blue need to be swapped.
*edit- Forgot pic, see post 5

4th thing of interest. TVIS wire needs to be installed. I also removed egr wiring.

Pins are read top right pin 1, top left pin 13, bottom right pin 14, bottom left pin 26.

EGR Blue-Black B23
P ??? B22
ISCV ac idle up Yellow-Blue B7
L neutral start Violet-Red B19
2 neutral start Violet-Green B6
SL A/T Blue-Yellow B1
S1 A/T Violet B2
S2 A/T Brown-Yellow B15

Need to add
Injector 1 red B12
Injector 2 green B11
Injector 3 yellow B25
Injector 4 blue B24
TVIS output Blue-Red B2 repurpose for ?

Need to move
IGF Black-Yellow B3 to B19

This is now the Ignition B output wire. IGT is now Ignition A. IGF is the feedback to ecu to make sure the coil fires and throws a code if it doesn't. I'm running COP wasted spark, 1 and 4 fire together, 2 and 3 fire together. Mspnp doesn't used IGF.

ECU plug C

This is the one in the middle with 16 pins.
Not too much needs to be done here. The harness I bought was from a California emissions car with 2 OX sensors. I removed OX2 and moved PIM to that slot so it matches up with stock 3sgte. Only other thing here is e21, sensor ground. Haven't traced down what this is yet.

Pins are read top right pin 1, top left pin 8, bottom right pin 9, bottom left pin 16.

E21 Brown C18 sensor ground for A/T
TT Black C7 Its for the check connector to the A/T
OX2 White C5 Cali car emissions requirement.

PIM from C2 to C5

Its a trap! At this point I would like to talk about unofficial pin out diagrams. For the longest time I would reference this pic for pinouts because its easy to read, only to discover it's wrong when pertaining to the 92-93 3sgte. I believe this is for the 90-91 only. I found this out when probing the mspnp 26 pin DBA connector.
Last edited by Magroo on Thu Mar 08, 2018 4:58 am, edited 1 time in total.

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Thu Mar 08, 2018 4:24 am


Mostly just removed all the cruise control and A/T wiring.

2 Pink idle cruise - I might have removed the wrong pink wire, notice its still there :shock:
3 Blue speed sensor cruise
5 Light Green pattern select
7 Grey VR1 cruise
8 Red-Green MC cruise
15 Brown-Yellow cruise
17 Grey- Red VRZ cruise
18 Pink-Black overdrive cruise


Everything here matches up pretty good.

5 Yellow Black overdrive cruise


This is a small blue plug that connects to the ac amplifier.
Last edited by Magroo on Sat Mar 10, 2018 4:13 am, edited 2 times in total.

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Thu Mar 08, 2018 4:26 am

Megasquirt undocumented features.

There is a 26 pin DBA connector on the opposite side of the ecu plugs. I hate this thing. Its awkward to use and sticks out too far making the mspnp difficult to mount. Fortunately I started probing around the pins and discovered most of them are connected to ecu plugs B C and D?(MSPNP has 4 plugs, one isn't used) This makes it much easier to incorporate things like electronic boost controller, wideband, ignition B, etc.


Here is a list taken from DIY autotunes website of that each pin does. After that is the location on the MSPNP ecu plugs they correlate to.

1 Cam sensor input B18
2 Table switch input
3 Clutch Switch D4
4 Tach output
5 Chassis Ground B13, 26, C1, D2, 3
6 Switched 12VDC (0.5A Max) D9
7 Boost control solenoid B2
8 Injector A output B12
9 Injector B output B25
10 Knock sensor input C13
11 CANBus high
12 CANBus low
13 Launch control input
14 Spark D output
15 Spark C output
16 Spark B output B19
17 Spark A output B20
18 Injector C output B24
19 External MAP sensor input C5
20 IAT sensor input C3
21 Oxygen sensor input C6
22 Signal Ground B13, 17, 26
23 5VDC Vref
24 Output 1 relay control (ALED)
25 Output 2 relay control (WLED)
26 Injector D Output B24

I may not have found them all, or there may be errors. I need to double check. Either way it makes incorporating the COPs, Boost controller, AEM wideband, and GM IAT sensor easier and cleaner in to the harness.

This is only the ecu side of things. I haven't started digging into the relay/fuse box, AC/FP box yet. At first glance it doesn't look too dissimilar.

More to come.

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Thu Mar 08, 2018 4:57 am

Forgot a pic. This is the wiring comparison of the 3SGTE vs 5SFE distributor plug wiring.


Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Sat Mar 10, 2018 3:58 am

Next up...

Connector N2

This plugs in to the automatic transmission.
It isn't needed anymore but we do need some of the wires from it.

1 --not used--
2 Black-White Neutral Start Switch from EB1 pin 4
3 Black to starter and IG2 pin 18
4 Violet-Red from ECU pin B19
5 Red-Black Reverse light switch out, from IG2-13
6 Red-Blue Reverse light switch from in, from IG2-4
7 --not used--
8 --not used--
9 Violet-Green from ECU B6

I'm going to re purpose the Black-White for the starter motor. In a 3sgte its a solid black wire from connector EB1 pin 2 straight to the starter. On a 5sfe there is no clutch safety switch. Its in the A/T.

On a 3sgte it goes from the ignition switch through a relay that's activated by the clutch neutral safety switch straight to the starter. The car is already wired for this already and the only thing that needs done is move EB1 pin 4 to pin 2 and splice the end of N2's black wire to the starter since it has the connector.

Chop this off.
Splice Black starter wire pigtail to Black-White wire. Move Black White to EB1 pin 2
Need to find a new connector for the Red-Black and Red-Blue wires for the backup light that plugs in to the manual transmission. I happened to have an old chopped up harness from when I bought a JDM motor a few years back that had the right plug. If you can't find one at a junkyard, The closest I could find was part number 90980-11250. The other 2 wires are already removed from ecu.


This connector sits close to the firewall on the passenger side back fender area in from of the power steering pressure hose. Only has 3 wires.

1 Black -Orange +12v switch power ignitor+injectors
2 -- not used --
3 White from connector 2B (relay box)power 100Amp fuse for fog and heater?
4 Black White starter motor

After splicing black wire pigtail to starter motor move Black-White pin 4 to pin 2. Pretend its all Black

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Sat Mar 10, 2018 4:00 am

Grey connector

This connects to the relay box next to the battery on the bottom side. Its exactly the same as the 3sgte.

1 White
2 White to 2E pin 5 for ignition switch
3 Black-Red to 2E pin 6 ignition switch
4 White headlight relay and various fuses
5 --not used--

White connector

This also connects to the same relay box. It is also exactly the same as the 3sgte.

1 Light Green-Black
2 --not used--
3 White Alternator
4 Pink IG2 pin 7
5 White Black Temp sensors at Radiator and Water neck?
6 Black-White AC compressor?
7 --not used--
8 --not used--
9 --not used--
10 Black-Yellow B+ check connector, ecu and IG2 pin 18

Plug and Play

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Sat Mar 10, 2018 4:02 am

Main fuse box


This can unclip from the relay box.

There are 3 wires bolted to this. A Black wire and a White wire on one side and a thicker White wire on the other side.

The 5sfe relay/fuse box is a different shape so you'll have to reuse your old one. Its as simple as just copying the wires that are there.

There are 2 spade connectors for fuses you have to depin from the old fuse box and plug in to the same spots on the 3sgte fuse box that are already there.

Be aware one of the white wires is thicker than the other. This gets bolted by itself to one side. This is the alternator that goes though the 100 amp fuse. The other thinner White and Black wires get bolted through the other side. This goes to battery and headlight relay?

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Tue Mar 20, 2018 8:56 pm

I haven't forgotten about this thread, trust me. Just been working too much overtime at work, and the weather in the Northeast has been extremely variable.

Just some quick pics of a fuel rail mock up and the COPs wired in for a test run. I'm using 1nz coils here but decided to switch to 1zz coils since they fit the 3sgte better.

I still have to finish wiring the injectors in to the harness, but I want to get the harness fit on the engine so I can get the wire lengths right.

Had the fuel rail setup for dual feed center return but changed it later. I'm using a tomei fpr and 850cc denso injectors for some kind of Toyota or lotus.

Re: Converting a 5SFE Harness for MSPNP on a 3SGTE

Wed Mar 21, 2018 1:23 am

Where in the northeast are you?

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