When you say, "Key Pad for shifting" is this a push button pad with R, 1,2,3, D on it? If so, wouldn't the tranny be a 741? I thought the 740's had a t-handle for shifting.
Tom's trans is an HT748R. That's the transmission used in all '87 NJT MC9s. It is an ATEC with the push button shift pad just like yours.
Tom, the TPS is wired directly to the DDEC ECM. J1A connector.
Pin H3 in J1A should have 5 volts.
Pin C2 in J1A is signal from TPS and will be something less than 5 volts.
Pin K1 in J1A is TPS ground.
The TPS plug under the drivers floor will be connected as follows:
C=H3 (5 volts).
If your TPS is the fault, you should set a DDEC code '21' or '22'. What DDEC codes are you setting?
An ATEC TPS code is the same as the DDEC ECM...'21', although I believe this is only applicable for HT741 trans with a TPS mounted remotely on the throttle linkage...such as Bill has. If your ATEC reads a code '21', but the DDEC doesn't, the wiring between the ATEC and DDEC may be at fault.
The DDEC 1 dx guide does not offer a resistance range. It suggests using a 'DDL' reader...which we ain't got. It counts pulses. Try using Pete's reference. May be the same TPS resistance for all DDECs?
It doesn't appear that DDEC 1/ATEC use an interface. Looks like the two ECMs communicate directly. This may be inaccurate...but I have both schematics of the trans and DDEC and they only share a few wires. The VSS is also processed by the DDEC.
The wiring DDEC/ATEC connections are inside the upper rear bay...in that crap hole that is typical of NJT MC9s. Mine appears to be in good condition, but moving them around scares the poop out of me. Old wiring really doesn't like to be molested.
Back to those fuse cases in the battery box...I've had an ongoing intermittant issue with the fuse holders and fuses.
They should all be replaced really. But, it's one of those things that I know how to quickly resolve. Still, the "Check Transmission' light has some pucker factor when it lights up way off from home!
Have you had any kneeling, high idle, or other electrical issues? These all interconnect with the transmission, although they don't set codes...they may if the DDEC senses speed when a limiter is 'on'...
I'd be rechecking the DDEC and ATEC for codes. Remember that unlike a DDEC II, if you pull the fuse on a DDEC 1, you cleared the memory. So make the codes set and read both ATEC and DDEC codes. See what you get.
If your windshields leak, you may well have a bad TPS. Water running off the center of the dash drips on them...screws them up. NJT also hosed out the floors regularly.
Still, IF the DDEC isn't seeing TPS codes, the TPS probably ain't the problem.
Until you re-read the codes on both units, the only other thoughts I have would focus on what electrical work was done on the coach prior to the onset of the problem?
BTW, Butch has the resistance for a DDEC 1 TPS. He checked his when his bus was acting up. I can check mine too and see what it looks like. Have to pull the spare tire out to access the connector, but that ain't much of a problem.