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Speed sensor fault

delcowizzid

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Put the stock memcal in and see if error code 24 goes away
 

MikeC

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Thanks delcowizzid. Gotta do a country job tomorrow. I'll note that for when I get back home on the weekend.
 

MikeC

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Reassembled the ECM with the MACE chip (I really want to keep this chip) tested it on a long trip at 100 KMH. Code 24 has gone away, speedo works and all the numbers on the trip meter look good. The problem may have been the ECM recalibrating itself for the new VSS.

The cruise control is still not working. All the CC connected switch circuits test out OK according the the GMH green manual's diagnostic procedures. I'll look at the circuits connected between ECM terminal A10, the cruise control module and the trip computer next- I'm not getting the specified 0-10V signal on ECM terminal A10 but the speedo and trip computer are still working.
Any ideas? Is there anything repairable in the ECM?
 

delcowizzid

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You will only get 0-10v on that wire with the wheels turning and will get higher with speed pin a10 is speed input to the ecu from the dash.
 

MikeC

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Thanks delcowizzid, I'll have a look at these. Beats me that the speedo and trip computer work, the cruise control switches all test out OK but the CC failed- at first it was intermittent failure with no dash light, then total failure. I've got the dash light back by resoldering all the connections on the CC circuit board .
My cruise control module has an "NY" number on the side , I got a similar looking module from a V8 VP with "PF" on the side. Do you know if they are interchangeable?
 

Pete O

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Hey guys, well it’s been a long road trying to sort this problem out with this ute, still to no avail. I have just replaced the ECU with a used item from a wreckers & it now runs rough at idle & hunts a bit. The code 24 hasn’t come back up but now it throws a code 42 which is a short to do with the ignition module. I’m thinking maybe this ECU is toast as well as this code never came up before I put the other ECU in. I’m taking it to an auto leckie as I’ve had it with all this bs. I’m a beat and broken man, lol.
 

MikeC

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Code 42 is the spark timing circuit- basically the ignition module. There are a lot of tests that can be done on this module but you really need to be an auto electrician to do them. But an easy initial check for code 42 is clean and check terminals B5,B3,D4 and D5 on the ECM-their the ones that control this timing circuit.
When mine failed 8 years ago I replaced it with an exchange Holden V8 5 litre racing module from nuclearpoweredmodules on ebay. Top bit of gear- the bloke really knew his stuff.
 

Pete O

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Code 42 is the spark timing circuit- basically the ignition module. There are a lot of tests that can be done on this module but you really need to be an auto electrician to do them. But an easy initial check for code 42 is clean and check terminals B5,B3,D4 and D5 on the ECM-their the ones that control this timing circuit.
When mine failed 8 years ago I replaced it with an exchange Holden V8 5 litre racing module from nuclearpoweredmodules on ebay. Top bit of gear- the bloke really knew his stuff.
Thanks MikeC,
I have another DFI with coil pack at home, I’ll throw that on to test it. Another question, when ya put a used ECU in, does it have to have a learning period as such or is it a plug in & go like I did?
 

MikeC

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No need for a learning curve. Reconnect the battery. Earth out the ALDL diagnostic port. Turn the key on. If everything's OK code 12 will flash 4 times. If the memcal is not fully seated or defective code 51 will flash.
 
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