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Freescan gives inaccurate values for some parameters, Espritmon is preferable.

Hi Guys, Time for an update. I've borrowed an ECU from a very generous forum member and you were all quite correct, my original ECU was indeed shot. With the loan ECU the car runs 90% better

Any error codes? You can check this without diagnostic software by bridging pins A and B of the ALDL connector and counting the Check Engine Light (aka CEL) flashes.

Hi Chaps,

Another little puzzle while I continue work on the main ECU issue.

I'm systematically checking all the wiring to the Esprit SE's ECU plugs.

Hoping someone can help me with three anomalies.

I've got two loose wires emerging from the loom near the ECU, both with ECU plug brass terminals attached.

These were safely taped up but I'd like to know which ECU plug and pin they came from.

One is black and the other is orange/black (note; main colour is orange with a thin black stripe not to be confused with the black/orange wire which is ok and in situ)

Also, a thick black wire (not OEM) had been pushed into J1/14 (just a twisted end/no terminal) and run to the dashboard area and safely taped up.

What have people been up to in this car's 30 years?

I've scoured the EMH manual but can't find any info on these thee items.

Maybe someone can advise or could tell me how many wires come from each ECU plug and that would help me narrow things down?

Regards, Andy.

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Can you confirm J1/14 - I thought the numbers went ABCD depending on the row ??

Only here once

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It's likely that your ECU is fried... It's good that they are cheap to replace. Do Not sell or give away or throw away your MEMCAL cartridge!!!  That is worth it's weight in gold, and you need it for your new ECU. That MEMCAL is Lotus Esprit specific!

The ECU wires should look more like this. SO maybe it's worth it to tray and get your wires figured out before plugging in a new ECU.

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Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Hi Barry,

The pins on each ECU plug are numbered 1 to 22. The EMH manual does prefix these numbers with a letter (A,B,C,D) but I haven't worked it's use out yet.

It certainly doesn't seem to correlate with the rows of pins in any logical way.

 

Hi Travis,

Great pictures thanks.

The two wires I am trying to trace are just right of centre in your second picture. (orange/black stripe and a near by black one)

They don't look like they go to any of the ECU plugs, but where do they go and what are they for?

Andy.

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Hi Guys,

While looking for a wiring diagram on Google, I stumbled across this thread.

Seems these two wires aren't used.

They were probably originally in a 2 pin connector which is now gone so just need to make them safe again.

Andy.

 

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The two 'spare' wires are:

BLK - used on non A/C vehicles so that the ECU knows there isn't an A/C system fitted.

ORA/BLK - used on vehicles with an electronic speedometer to feed a VSS signal to the dashboard.

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Derek beat me to it, OB (or ON?) is for the speedo, it goes in J2/8 if you want to convert to an electronic speedo. The thick black wire pushed in is probably an earth, but I can't find a reference to anythin on J1/14.

For reference, the layout of the 4 connectors:

ECM connectors.pdf

Derek, do you now where the black wire needs to go to disable the A/C? I've taken everything out of my SE, apart from the fuse and relay because that throws a CEL. Can't seem to find it in the wiring diagrams.

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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New (refurbished) ECMs can be had from the states for about £65 delivered. I bought one about this time last year for mine and it was delivered inside a week. As previously stated, make sure you hold onto your memcal, you'll need it for the new ECM.

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9 hours ago, sailorbob said:

The two 'spare' wires are:

BLK - used on non A/C vehicles so that the ECU knows there isn't an A/C system fitted.

ORA/BLK - used on vehicles with an electronic speedometer to feed a VSS signal to the dashboard.

Brilliant, thanks very much.

47 minutes ago, Escape said:

Derek beat me to it, OB (or ON?) is for the speedo, it goes in J2/8 if you want to convert to an electronic speedo. The thick black wire pushed in is probably an earth, but I can't find a reference to anythin on J1/14.

For reference, the layout of the 4 connectors:

ECM connectors.pdf 99.93 kB · 1 download

Derek, do you now where the black wire needs to go to disable the A/C? I've taken everything out of my SE, apart from the fuse and relay because that throws a CEL. Can't seem to find it in the wiring diagrams.

Filip

Hi Filip,

Thanks for the connectors pdf.

Re; A/C disable; According to page 7 in section EMH.4 of the EMH service notes book (actually page 82 in the pdf file) the black wire may go into J2B18 in order to inform the ECU of no A/C.

Please evaluate as I'm a novice.

Andy.

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1 minute ago, tomcattom said:

New (refurbished) ECMs can be had from the states for about £65 delivered. I bought one about this time last year for mine and it was delivered inside a week. As previously stated, make sure you hold onto your memcal, you'll need it for the new ECM.

Thanks Tom,

I can only find one tatty GM 01228708 ECU for sale in the world (US ebay) and it's nearly £200 delivered by the time all the import duty and shipping is added.

Do you have any contact details for where you got one from. I'd buy one as a standby even if I got mine working.

Andy.

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10 minutes ago, AndyPG said:

Thanks Tom,

I can only find one tatty GM 01228708 ECU for sale in the world (US ebay) and it's nearly £200 delivered by the time all the import duty and shipping is added.

Do you have any contact details for where you got one from. I'd buy one as a standby even if I got mine working.

Andy.

I'll have a look at my ebay history when I get home tonight and and see if I can find the seller I got mine from.

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Hi Andy,

Thanks for pointing out the non A/C request, I completely missed it! It's only 2 pages from the connector overview I posted (which I guess you already had anyway). I'll give it a try later this week.

Filip

Edited to add: appearantly I had already listed it in the pin-out file of the ECM as well, but never thought about actually connecting it. Do'oh!

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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@AndyPG The seller I used doesn't have the one I bought listed anymore, but another seller has the same part for a tenner more than I paid. I mis-informed you in my first post, I paid £65 + delivery and import which came in around £100 all in. With postage and import it looks like this one will come in at about the same sort of price.

https://www.ebay.co.uk/itm/Engine-Control-Module-ECU-ECM-PCM-Computer-Cardone-77-8708-Reman/292660222501?epid=76006286&hash=item4423e89a25:g:JLwAAOSwFnxbl02P

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Thanks Tom,

I had actually seen that one but had dismissed it, as I wasn't confident it was the right one.

It has a quoted manufacturer's part number of 77-8708 which does seem tantalizingly similar to the GM part 01228708 I need.

Is it known to be the same ECU even though the part number has been kinda shortened?

Andy.

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10 minutes ago, AndyPG said:

Thanks Tom,

I had actually seen that one but had dismissed it, as I wasn't confident it was the right one.

It has a quoted manufacturer's part number of 77-8708 which does seem tantalizingly similar to the GM part 01228708 I need.

Is it known to be the same ECU even though the part number has been kinda shortened?

Andy.

Its the same one I bought for my S4s and while I haven't driven the car on it since it was fitted (due to the on-going resto work) I've run it several times with no ill effect and its fixed the issue I had with my fans not triggering from the ECM, which was the reason I replaced it in the first place.

The item description does list the compatible Delco part number "1228708" which is the one you want.

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5 hours ago, Escape said:

OB (or ON?) is for the speedo

The wire is ORA/BLK from the ECU to the engine management harness connector (EMHC) and then changes colour to ORA/BRN from the EMHC to the rear harness connector (RHC) and onwards to the binnacle harness connector (BHC).

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Thanks Derek,

Looks like I made a typo earlier regarding the thick black (non OEM) wire pushed into J1/14. It was actually pushed into J2/14 which means (as you pointed out in a PM) it was an attempt at tapping into the VSS pulse for an electronic speedo. Sorry for the red herring.

So, in summary,

It seems, most SE owners will find two spare wires close to the ECU with no apparent home. Orange with a black stripe and another wire all black.

Both wires have an ECU terminal affixed so they can be installed into an ECU plug.

The orange/black wire can be inserted into J2/B14 to give a VSS signal for an optional electronic speedo. (This wire emerges as orange/brown at the binnacle)

The black wire (likely a ground) can be inserted into J2/B18 and will inform the ECU that the vehicle has not got aircon installed.

Andy.

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9 hours ago, AndyPG said:

The orange/black wire can be inserted into J2/B14 to give a VSS signal for an optional electronic speedo. (This wire emerges as orange/brown at the binnacle)

I think that was a typo, the speedo signal is J2/B8. 😉

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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Thanks Filip,

I appreciate you pointing this out. I'm learning lots here.

Reading through, ECU pin J2/B8 is indeed the OEM electronic speedo sensor pin giving a VSS signal output.

And you are absolutely right, this would be the obvious 1st choice for acquiring the signal.

On my car, someone had used J2/B14 which I initially thought was an error, and maybe it was.

However, I understand that J2/B14 is an alternative VSS signal pin albeit inverted.

Andy.

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J2/B8 is what is used for the electronic speedo on later Esprits, and what I've used on both my SEs. You could theoretically use the wire(s) from the VSS directly, but that would mean the speedo has to be able to handle the raw data. I think using both wires in the pair would give you a better chance, but still easier to use the output signal. I'll answer your PM when I have time to elaborate.

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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Sligthly off topic, but concerns an earlier post:

I connected the spare black (earth) wire to J2B18, and took out the A/C request relay. As I understand, this should tell the ECM there's no A/C fitted. But I still get the CEL. Haven't read the code yet, I'm sure it will be 26-quad drivers, caused by the A/C request relay being removed. I had hopes J2B18 would work, so I could get rid of the unused A/C relays.

Any suggestions?

Filip

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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You will possibly need to reset the ecu error first for it to go away @Escape now you have completed the mod

Only here once

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11 minutes ago, Barrykearley said:

You will possibly need to reset the ecu error first for it to go away @Escape now you have completed the mod

As said, I haven't hooked up Espritmon since connecting the black wire, but there was no CEL before, because I had kept the A/C request relay in place (after removing it, getting an error, replacing it and resetting the ECU). I'll try tomorrow or Monday. Decided not to do anything car-related today (except read and post on the forums 🙂 ).

I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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