1uz air con error code 72

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fenlux

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5
Location
Australia Tas
So I have put a 1uz in a old hilux with a uzz31 ecu from what I can tell, numbers are gone from the ecu case, but the 40p 40p 40p output is correct and corresponds to everything as per wiring diagrams.

Everything works and runs fine apart from error code 72.

Hilux air con sends a 12+ signal to ecu pin 34 A/C and idles engine up then activates pin 23 ACMG and engages ac clutch. Now all this works fine the first time I start the car after a ecu reset but when I turn the car off and start it again the check engine light comes on but everything still works fine apart from the error code.

Any ideas anyone?
 
If it's wired correctly then the Hilux A/C amplifier will be controlling everything. Should there be a fault in the A/C then the light in the A/C switch will flash. Now I suspect that you are getting code 27 which is the sub O2 sensor code. Now the earlier UZZ31s didn't have the sub O2 sensors but the later ones did, how you can tell which one that you have is to look at the main O2 sensors. Single wire sensor then no Subs, Factory 4 wire they had subs. I also had this happen on my first one 4 years after converting it (1990 Surf with 91 UZZ31 engine). In my case the ECU was dying
 
Thanks for you reply samsdad, the hilux a/c can control the air con but it doesn't idle up the engine when it turns on and stalls the engine at idle so I am running it through the ecu so it can increase rpm and then turn on a/c compressor. As I said it all works fine apart from causing the check engine light to come on. It is defiantly code 72 not 27 and I have the earlier version with the single wire O2 sensors. I could just run the CEL through a switch so its not on all the time but I would like to get it right so the light comes on when there is a fault.
 
Took a bit of finding but code 72 comes up as "Fuel cut solenoid" or "Fuel pump control" fault. I've never had an issue with this one as I trigger the fuel pump relay from the FPR pin on the ECU. From memory the Soarer run another ECU to run the fuel pump and in all honesty it's been so long since I wired up a Soarer ECU that I've forgotten the way around this. Might pay to search the forum as I do remember this being discussed a few years back
 
I'm with Samsdad. I've never seen a code 72 on a 1uz and all my listings point towards fuel shutoff as well. Something doesn't make sense.

Was the third 40 pin ecu plug part of the main engine harness or a separate plug?

Can you please measure the width of the ecu body?
 
I'm with Samsdad. I've never seen a code 72 on a 1uz and all my listings point towards fuel shutoff as well. Something doesn't make sense.

Was the third 40 pin ecu plug part of the main engine harness or a separate plug?

Can you please measure the width of the ecu body?
 
I have been driving it for a couple of months before I got the air con re gassed and didn't have any error codes, its only started since I've been using the air con.
Error code 72 is hard to find but this is the one I have found.
72
AIR CONDITIONER COMPRESSOR RELAY/RELAY SIGNAL
A/C COMPRESSOR RELAY/CIRCUIT
ECU
The 3rd plug is separate to the engine harness and its a bit hard to measure the width of the ecu because of where it is in the dash but I would say it would be around 220mm wide. Pinout found here http://soarercentral.com/sc-forum/messages/282/361120.html
 
I'm thinking I might just run a solenoid valve activated buy the air con switch to idle up engine and not use the ecu to control the a/c.
 
Interesting. Every one of the uzz soarer looms with the 40/40/40 ecu I have wired have always had the third 40 plug as part of the main engine harness. However the 40/40/40 uzs141 crown has the third plug as part of the dash(main body) harness. The ecu pinouts are similar but there are a couple of differences. Looms are noticeably different. I've interchanged at times but had things to sort. Crown ecu into soarer gave a/c issues(and trans temp) but I never went further as repaired soarer ecu.

The body size of the ecus are different so that's how I know if it's soarer or crown. I always check the parts before wiring.
 


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