I am getting a service light and error code displaying 66 00. Any idea what this is for?

D1 66 00 getting same but I don't have a code manual to be able to know what is causing it.

code 66-00 indicates a "serial communications interface" fault.

Main code 66 indicates the ECU is expecting to get its throttle position sensor (TPS) signal across a serial
communication interface from a computer-controlled engine. Either the engine computer is not sending the TPS
information or the wiring between the engine and transmission computers has failed.
Code 66 00 can occur when the transmission ECU remains powered when the engine ECM is powered down.
The transmission sees this as a communication link failure.
Hope this helps you start troubleshooting.

Thanks. But the engine starts OK. The throttle works. When the gear is engaged the reverse or 3 flashes. When it does sometime get into gear, it will only go in reverse gear or forward drive. When I switch off, I have play again with the lever until it gets in gear. I have by-passed all the air switches just in case it was a faulty air switch. I have tested the ECU, sensors on MD3060 on different trucks- they work. There is a little black pcb full in epoxy. This one I have not tested on other equip yet. YOur useful advice please.
Thanks

I can't for sure say how it effects the engine start but...This info is from the 1998 Allison WTEC2 Troubleshooting manual. the66-00 code does not set a "do not shift" light and the "inhibited operation description" is - use default throttle values, DNA (ECU stops adaptive shift control while the code is active)

troubleshooting,
1.Check for a TPS signal from the engine to the transmission, an engine computer malfunction, or an engine TPS fault.
2. Check wires 142 and 151 between the engine and transmission ECUs for an open or short and check that all connections are clean and tightly connected.
3. Use the Pro-Link to see if the ECU is receiving power when it should not.

Has anyone got wiring diagram for the MD3060. Mail address anarraina@hotmail.com --

quote:

Originally posted by Service Eng:
Has anyone got wiring diagram for the MD3060. Mail address anarraina@hotmail.com --

Entire trouble shooting manual sent.

Thanks a lot. This will surely help me a lot. Thanks Thanks Thanks.
I'll let you know how I get along with this problem. I found out that there is another filter inside the gear box. I will check that too.

I have started check only to find out that the cable and wiring harness is of different type.
Date code : 03-10-2004
Model No : WT3ECU911A
\throttle : Auto detect.
Gov Rpm : 2500
Pri-Mode : 1-3S2
Sec-Mode : 1-4S3
TID : 3
In fact I need a WTECIII trouble shooting manual.
I have checked all the cables from the Transmission to ECU and all OK ( COntinuity test and no short )
I have checked all the cables from the air valves to ECU also. The rest I cant figure out.

Thanks

I have also changed the ECU to another truck. It works fine. I have also changed the gear shift lever and that works too. I have taken the whole box with ECU & VIM complete and tested on another truck and it works. There must be an intermittent cable from the engine ECU to the transmission ECU that I cant find without proper WTECIII wiring.

still having the same trouble (D1 66 00)

How do I know which wires are:
Check wires 142 and 151 between the engine and transmission ECUs for an open or short and check that all connections are clean and tightly connected

Also - if anyone can forward a copy of the trouble shooting manual I would greatly appreciate it.

pheney@comcast.net

Thanks in advance!

Hey Pheney. I have sorted out my problem. It was only an intermittent air valve switch. But unfortunately for me it had a normal closed contact. Hence bypassing it with a piece of wire was not of any help (specially if you dont have any wiring diagram to see this ). What ECU have you got? If you have a WTECII I can help with the trouble shooting manual. I am still looking for a trouble shooting manual for a WTECIII.

Service Eng - Sorry for the slow response ( I travel a lot for work) I am not sure which ECU I have nor do I know how to tell? Its a 1997 version if that helps any.