LS3 ECU and Factory harness
Discussion
Just trying to wrap my head around the ECU wiring, if you order a GM crate LS3 how does the ECU connect to the factory harness for gauges, check engine, rpm speed etc... I know GM also sells a harness for installing the motor in non LS cars but I imagine it is too short, do you lengthen the wires and then work out the pin outs and graft it in your self or is there a connector harness ready to go somewhere?
either you buy a digi dash like i have, the gm harness/ecu has can bus, which will connect to a matching dash or you have to put extra sensors into engine to get gauges to work, the AIM dash i have purchased seems like a good way of doing it
http://www.aimtechnologies.co.uk/aim-products/aim-...
http://www.aimtechnologies.co.uk/aim-products/aim-...
Edited by corvettedave on Friday 5th December 13:00
Edited by corvettedave on Friday 5th December 13:01
Depends on wiring loom and engine. Crate (well for LS7) comes with E67 ECM with 3 connection blocks while Gails loom uses e38 ECM with 2 blocks- this may have changed but you can see the difference below
http://www.lt1swap.com/pcm_identification.htm
http://www.lt1swap.com/pcm_identification.htm
I suppose the question is WHO sells a harness. GM sells one but it is too short and it may not have same connectors as what is on the Ultima harness. If American speed sells them stand alone (I hear they are labeled and jsut plug in) along with the accessory kit for AC & Alternator then that simplifies the issue.
Who else sells an accessory kit & LS3 harness over on your side? I saw Auto Bionics or Boost Performance may?
Who else sells an accessory kit & LS3 harness over on your side? I saw Auto Bionics or Boost Performance may?
Connection to the Ultima harness is not the issue as there are very few connections required.
More of an issue are...
• The ancillary bits are in different positions on an Ultima engine install so the GM loom connections don’t reach or are too long.
• The loom needs to depart from the engine at the front on an Ultima. The GM loom is designed to depart from the back of the engine.
A standard GM loom will be lots of work so go for one designed for our install.
Steve
More of an issue are...
• The ancillary bits are in different positions on an Ultima engine install so the GM loom connections don’t reach or are too long.
• The loom needs to depart from the engine at the front on an Ultima. The GM loom is designed to depart from the back of the engine.
A standard GM loom will be lots of work so go for one designed for our install.
Steve
When I installed my LS3 over 4 years ago it wasn't suported by anyone then, I had to adapt the wiring harness it was a bit daunting to say the least, but taking 'one wire at a time' I managed to complete a loom, didn't breakdown so I must have done something right........this is just after I started and asked myself WTF ??
bluesatin said:
I have a crate LS7 Loom and ECU (e67) sitting waiting for somebody who wants to modify the loom to fit. HAd it for years so make me a n offer to help with crimbo presents!
I've converted one loom and would not consider it cost effective....it takes hours. Not an issue if you are doing it yourself but if you are paying for it your best bet is to bin it and buy one in from AS or autobionics etc.Steve
I'm just posting this as it may help anyone who stumbles on it in future as ebeck (the original poster) has probably resolved any issues by now.
The GM ECU loom IS compatible with the Ultima one although you have to lengthen a number of cables since the GM loom is designed to be mounted in a different position. This is not rocket science, and only requires some small gauge wire in various colours, a soldering iron and heat shrink for insulation, and if you work with one cable at a time it took me about 5 hours over 2 evenings and it looks very neat and tidy. Everything then plugged straight in and connected in with the Ultima loom and all the GM cables are labelled which makes it idiot proof. Yes you can buy a bespoke Ultima ECU loom from other suppliers which is easier, but if you have the stock GM one already, you don't have to scrap it as it's absolutely fine if you don't mind modifying it slightly ... You're only cutting one cable at a time and inserting 6" of wire here and a foot there... Easy!
The only trouble I had was with the A/C pump and the alternator connections which weren't as straight forward and required a search or two on the web to identify which pins did what and then a quick check with the Ultima wiring diagram and it was pretty straight forward after that.
I will add that I am on the verge of a first start up, so I'm assuming that everything will work fine, but I have every confidence it will because of the quality of the Ultima loom and my ability to work a soldering iron correctly 😜
The GM ECU loom IS compatible with the Ultima one although you have to lengthen a number of cables since the GM loom is designed to be mounted in a different position. This is not rocket science, and only requires some small gauge wire in various colours, a soldering iron and heat shrink for insulation, and if you work with one cable at a time it took me about 5 hours over 2 evenings and it looks very neat and tidy. Everything then plugged straight in and connected in with the Ultima loom and all the GM cables are labelled which makes it idiot proof. Yes you can buy a bespoke Ultima ECU loom from other suppliers which is easier, but if you have the stock GM one already, you don't have to scrap it as it's absolutely fine if you don't mind modifying it slightly ... You're only cutting one cable at a time and inserting 6" of wire here and a foot there... Easy!
The only trouble I had was with the A/C pump and the alternator connections which weren't as straight forward and required a search or two on the web to identify which pins did what and then a quick check with the Ultima wiring diagram and it was pretty straight forward after that.
I will add that I am on the verge of a first start up, so I'm assuming that everything will work fine, but I have every confidence it will because of the quality of the Ultima loom and my ability to work a soldering iron correctly 😜
I am trying to work out the connections between the Ultima loom and the ECU/harness. Which Ultima loom wires will become redundant?
For instance, I assume the fuel pump will be connected to the ECU harness and not the Ultima loom, but I'm not certain as to how.
I should be receiving my loom, ECU (PWP) and harness (PWP) shortly but I would like to get some wiring diagrams together in the meantime.
I assume all the engine sensors will be connected to the ECU via it's harness and I will be using a Race Tech Dash 2 with CAN ODBII connection to the ECU to get my readings.
I think if I knew which Ultima wires will be redundant I should be able to put the other pieces together.
Apologies if this is really basic but I am a true novice at this!
For instance, I assume the fuel pump will be connected to the ECU harness and not the Ultima loom, but I'm not certain as to how.
I should be receiving my loom, ECU (PWP) and harness (PWP) shortly but I would like to get some wiring diagrams together in the meantime.
I assume all the engine sensors will be connected to the ECU via it's harness and I will be using a Race Tech Dash 2 with CAN ODBII connection to the ECU to get my readings.
I think if I knew which Ultima wires will be redundant I should be able to put the other pieces together.
Apologies if this is really basic but I am a true novice at this!
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