i posted this in the conversion/hybrid section but probably is more appropriate here so excuse me if i am duplicating my questions. moderators please do as you think appropriate.

ive done numerous searches (from all over the web and here as well) but cant find answers to these tough questions:

base info: '04 Holden LS1 swapped into a Jeep Wrangler using the LS1 computer exclusively but no PIM or BCM (deleted those from the wiring as i have aftermarket gauges and thought there was no use for them). i've yet to wire in the MIL but did wire in the DLC. ive been able to connect my laptop software via the DLC and observe engine functions without issue but cannot pull codes (even when i deliberately unplug things like injectors, sensors, etc...). the engine runs great but i have a slipping prob with the tranny so want to pull codes (which im sure are there - just cant access them).

my questions are: is the reason i cant pull codes because i need the PIM (&/or the BCM) to convert the class 2 serial data signal from the PCM to a UART serial data signal at the DLC (would be pin 9 on the DLC and pin 6 for "diag enable" from the PIM)? why am i able to connect my laptop to the DLC and watch engine management or is that separate info from DTC signals (looks like the same wire providing both information from the PCM)? and does it have anything to do with the fact the MIL circuit itself is not present? do i need the PIM (&/or BCM) to run the MIL or can i simply run 12V to a bulb and ground it thru the PCM's serial data output? im worried there are differences in circuit voltages if i do this and dont want to fry the PCM. at present, the DLC is wired as follows: pin 2 is the PCM class 2 serial data output signal. pins 4 & 5 are grounds and are wired together (is this okay? ive seen differing opinions). pin 16 is direct 12 volt battery power. any help is appreciated. would like to pull codes (im sure there are many) before we go to the dyno shop for software editing. i seriously doubt i simply have no codes stored but spoze its a possibility (like winning Lotto) - surely i dont have it right on the first go. thanks in advance.

 

you have it wired correctly and if there were codes you would see them

you dont need pim or bcm...


what are you using to read the PCM?

also MIL light
12v to one side of globe and PCM MIL output on other

 

im using Palmer Performance Scan XL on the laptop but also tried a ScanGauge II handheld unit which also produced no codes.

as for the MIL, this pcm does not have an MIL output from the pcm which would normally be pin 46 on the red J2 connector (Holdens are a bit different to US models in some wiring respects). the wiring diagrams show the class 2 serial data output from pin 58 (blue J1)going to the PIM where it converts to UART sd and then into the bcm and then into the mil light itself in the holden cluster (which i didnt use as i have aftermarket gauges). this is why im concerned about putting a full 12v to a bulb and then tied into pin 58 at the pcm (the only sd output i have) - im worried voltage drop across the bulb will be too low and fry the pcm at the ground end of the circuit although there are plenty of other 12v circuits going into the pcm.

the dlc wiring diagram is similar to the MIL using the PIM and BCM and a mix of UART and class 2. looks like there are actually 7 wires into the dlc instead of the normal 4 (2 ground, battery and data signal). ive omitted these 3 extra wires: pin 1 going to the bcm, various cabin modules and the instrument cluster (presumably the MIL). pin 9 serial data being tied to the PIM and BCM and pin 6 going to the PIM (sez "diag enable"). the rest is wired as you would expect except for pin 2 going to both the PCM (pin 58) AND the PIM as well.

i still dont understand why i cant intentionally set a code by disconnecting things. you would think i would have SOMETHING in there! makes no sense.

 

ok i took a chance and wired 12v (fused) to a working bulb and then into pin 2 of the dlc (which is tied to pin 58 on J2 - the class 2 sd output from the pcm). the bulb doesnt light with the key on or the engine running. looks like no ground on the pcm end of the circuit. its spozed to come on for 2 seconds with the key in the on position then go out. thats not happening either. i suspect i need to convert the signal from class 2 to UART so i think im gonna have to wire in the PIM to make it function correctly. just need to find a schematic for the PIM now. i know PIM pin 6 goes to the BCM and pin 9 on the DLC. pin 7 goes to the class 2 output from the pcm (pin 58) as well as pin 2 of the DLC. pin 8 appears to be 12v via the starter relay. pin 16 is the ground. pin 15 is an orange wire that i cannot verify and also looks like im missing pin 11 which is the "diag enable" circuit going to pin 6 of the DLC. so more research! too bad Holden copyrighted everything. finding info for this is like pulling teeth. you boys in the states got it made! would be much easier if Holden had kept the same wire colors and circuitry as the chevy counterparts.

 

you cant wire it the way you have done.. you are lucky you dont cause damage to the ECU

just wire the MIL trigger to pin 46 like you previously mentioned then change the tune to suit... its not going to work any other way

cant use the PIM for what you are doing.. it is purely a language convertor.. does nothing with the MIL light

 

there is no pin 46 on the pcm (or any other other MIL output on the pcm for that matter). not even a pin to connect to on the PCM @ #46 - its empty in that cavity. just pin 58 on J2. i wired the PIM in but still nothing although i am missing the data enable ckt and still have the mysterious orange wire from the PIM unhooked (i reckon this may be the "data enable ckt" although its on the wrong pin). the laptop still spits out engine functions but once again, no dtcs. so appears the pcm is still working normally (lucky me).

 

yes you will need to get a pin to place in that position

I live in Australia and wire up many LS1's into various vehicles along with mail order looms..

you will not get the mil light working using the bcm, pim or wiring onto the serial data line.. so give up on that one

 

fair enough doubledip and btw, thanks for your info!

will try putting a pin onto #46 but tell my why it worked in stock config but now needs modification? shouldnt it work as per the stock config?

again, thanks a heap mate really appreciated!

 

it works in stock config because you are forgetting the Instrument cluster is a computer as well..... it is recieving the information from the ECU that has been converted by the PIM and is seeing if the SES light needs to be illuminated and when is then turning it on... not because it sees an earth down the serial/uart line

 

ahhhhh..... you are correct, i was forgetting about the instrument cluster aspect of this. THAT was the piece of info i was missing - it all makes sense now. ive wired it up as you suggested and now have the mil working! still no codes coming out so i assume i simply dont have any (was expecting tranny codes as it is slipping). still not sure why i dont have codes for other things i disconnected trying to induce a dtc tho. but think we are ready to take it to the dyno shop and see if a proper software edit will help with the trans concern. thanks again for all your help mate - you're a legend! cheers

 

no worries.. you also need to make sure that code P0650 is unticked & set to 1 - MIL on second error

 

i presume you mean as part of the software edit? bit lost as to what you mean here (im no pcm tuner). and, is this maybe why i cant get codes? cheers again

PS - iou a beer if ya ever come to Perth muhahaha!

 

Can you shed more light on this? I just did a swap into a 77c10 and used a 5.3L/4l60e and everything is working fine. When I did an obd2 test it pulled up this same code..
p0650
defintion: Malfunction indicator lamp control circuit fault
Explanation: Ecm has detected an improper voltage level on the MIL circuit with the light commanded on
Probable cause: open or short circuit condition
failed driver circuit in the ecm
What can I do to fix this. I hooked up the pcm wire to one side of the light and a 12v+ ignition to the other side. Do I need to use 12v+ battery instead of 12v+ ignition? Thanks for any info you can share. ALso the MIL light does come on when I put the key in the ON-position and once I turn on the vehicle it turns off. If I do an obd2 test it does give me trouble codes but the light is not on even though it has trouble codes.

 

yes as part of the tuning process

no you should still get codes logging in the PCM when a fault arises...

I would think that it is possibley the scanner that is faulty/not good enough

definately disconnecting the maf sensor should bring light on

 

took the pcm down to the tuner the other day and set code P0650 to unticked (set to 1 - MIL on second error). obviously no codes were stored with the pcm out of the car but still no codes after running it (even when induced). tuner sez it could be the way he did the Mafless tune - he used an old school method using lower tables. s/b be able to sort it once its on the rollers running. anyways, reset the pcm for 4.56 ratios w/33" tires to match what we are running. shifts much better but needs a lot of fine tuning yet. we agreed the next step is to take the car down and put it on the rollers and do a proper tune. will see what else we can find out at that point. he isnt sure if the pcm will handle the gear ratios and tire sizes but thinks he can get around it. will know more next week!

 

today the dyno tune was done using HP Tuners on the rollers by a professional tuning shop. overall, it went well but we figured out we have no 2nd or 4th gear from the 4L60E (probably a bad band or servo seal). thats been farmed out to a tranny shop to get sorted. but still no MIL - cant read codes even when using HP Tuners. we are wondering if the MIL circuit itself shouldnt have constant battery power instead of ignition power - or would this leave the MIL bulb lit all the time? the thinking is maybe we are clearing codes everytime the key is turned off. we currently have the same setup as before: 12V ignition (fused) to one side of the MIL bulb and the other end of the bulb going to pin 46 on J2 of the pcm. the dlc is still wired the same as before and we can still log everything on both my Palmer software as well as HP Tuners. the tuner sez it doesnt have anything to do with the mafless tune he did earlier (and that has been switched to a speed density tune as of today). we are stumped. will try constant 12V battery power to the MIL bulb but if that doesnt work we have no clue (and probably never did LOL). HELP!

 

Is there constant power at the orange wires into the pcm? If not then that would be why you never have codes stored. The pcm needs constant power for memory. The pinks are keyed power and orange are constant B+

 

yes .. you should definately have a MAF code P0102 stored.. check codes while car is running.. this will bypass a wiring issue clearing codes...

as for the light bringing up codes i have a car in at work this week that we are doing a conversion in (Old valiant with LS1) i will test the light out on it and see if it needs to have a US tune or Aussie tune to work as i double checked the settings with a known good tune and all is correct

P0650 - unchecked
1 - MIL on second error

also checked link from where i got info from and is correct... all of the looms we do that have the MIL set are mail order and no one has said anything .. so i cant help you any more till i try this one physically infront of us.

 

the pcm has only 3 power feeds: all are orange (there are no pink wires in the holden loom). currently we have directly fused battery feeds going to Pin 20 on J1 and Pin 57 on J1 (circuit #740). a third feed from ignition is going to Pin 19 on J1 (circuit #39) - maybe this needs to be a direct battery feed instead although the factory diagram shows it as a pink ignition feed (it is definitely orange on our loom). if so, we would have no ignition feeds to the pcm which i thought was required.

we did confirm the lack of codes with the engine running and also confirmed again that po650 is unticked 1 - MIL on second error.

 

starting to sound like something is wrong with your pcm....

if it is a Mafless tune then code 102 will be unticked and because there is no MAF then code 102 will be present... if you dont have code 102 then i think there is a problem with you PCM or tune no flashed in properly for some reason

the code p0650 has nothing to do with it