MV8 Posted June 15, 2023 Share Posted June 15, 2023 Less likely to do additional damage testing unknown wiring with resistance (and the battery disconnected). Never too late to take it to someone who can troubleshoot with very limited information from the mfg. Summer's half over already. Link to comment Share on other sites More sharing options...
ralph Posted June 15, 2023 Author Share Posted June 15, 2023 At the moment, I have no easy way to transport the car (the trailer the crates came in is too big for anything I can tow with), but on the off chance that I find a way to move it, any recommendations in the Santa Cruz area? Greg Solow's shop can find their way around Morgans pretty well, and they used to work on my old 1970 Europa back in the day (though I recall Greg would go into something resembling a Tourette's fugue when I'd show up -- that europa was highly customized, and not in a good way...come to think of it, electrical issues abounded, and were exceedingly difficult to troubleshoot because the first/prior owner had rewired the whole thing with a single spool of one color wire...this should be cake, comparatively...) Link to comment Share on other sites More sharing options...
MV8 Posted June 15, 2023 Share Posted June 15, 2023 (edited) Unplug the TPS, key on, check for 4-6.0 volts between any TPS plug terminal/pin and ground. Yes/no? This is a check for what's called Vref or the basic power level provided by the ecu to several sensors to provide an output to the ecu on a different terminal/pin. By having the ecu provide the voltage, it ensures it will be consistent. Also check the terminal on the opposite side of the terminal that showed 4-6v. This will be signal return to the ecu. Check for voltage between the battery positive and this pin, key on. Is this voltage within 1 volt of the battery voltage? Unplug an injector, key on, check the voltage between either pin and the negative battery terminal. What is the highest voltage? Does the ecu have a part number? How many pins does it have? I expect it will have 104, 122, or 150 pins. The battery voltage should be at least 10.5v for these tests without engaging the starter. Edited June 15, 2023 by MV8 Link to comment Share on other sites More sharing options...
JohnCh Posted June 15, 2023 Share Posted June 15, 2023 43 minutes ago, MV8 said: Does the ecu have a part number? How many pins does it have? I expect it will have 104, 122, or 150 pins. The ECU is an MBE 9A4. 36 pins. Pinout information is here: https://sbdmotorsport.co.uk/wp-content/uploads/pdf/MBE9A4-PinoutIssue_F.pdf -John 1 Link to comment Share on other sites More sharing options...
MV8 Posted June 16, 2023 Share Posted June 16, 2023 Thanks John. Even better. Is there an add-on security key fob system that disables the efi but allows cranking? Ralph, also check for key-on bat voltage to the middle pin on the unplugged coil pack connector. Does anyone know if Cat uses the sbd harness? Just a four pin interconnect to the cat chassis harness? Link to comment Share on other sites More sharing options...
JohnCh Posted June 16, 2023 Share Posted June 16, 2023 The factory immobilizer disables two functions: cranking and either fuel or spark -- I seem to recall it's the latter -- but not all three. The 420 uses a 36 pin harness for the MBE that attaches to the chassis loom, then a separate connector with a lot of pins that mates the engine loom to the chassis loom. Connections between the engine loom and MBE are hidden within the bowels of the chassis. Also, to avoid confusion, the 420 uses coil on plug not a coil pack, however, the engine loom does put all 4 CoP connections through a single connector located towards the back of the head. Link to comment Share on other sites More sharing options...
MV8 Posted June 16, 2023 Share Posted June 16, 2023 Thanks, I was thinking about a zetec with a single coil pack. Ralph, there should be a pin in the single connector at the back of the head that connects one lead of each coil together. This pin should have close to battery voltage with the key-on. Link to comment Share on other sites More sharing options...
JohnCh Posted June 16, 2023 Share Posted June 16, 2023 I was wrong about the location. I was going from memory and confused that connector location with the one used for the injectors. The CoP connector is shown below between the front two cylinders. -John Link to comment Share on other sites More sharing options...
ralph Posted June 16, 2023 Author Share Posted June 16, 2023 I may have this sorted. After swapping the WP / W wires at the battery disconnect, I'm now seeing 12v at the injectors. Simple mis-wire at the factory. This is as maddening as it is cathartic, so...on brand, I guess... 2 Link to comment Share on other sites More sharing options...
MV8 Posted June 16, 2023 Share Posted June 16, 2023 Hooray! The maddening part is not offering full schematics to anyone anymore. Link to comment Share on other sites More sharing options...
JohnCh Posted June 16, 2023 Share Posted June 16, 2023 42 minutes ago, MV8 said: Hooray! The maddening part is not offering full schematics to anyone anymore. Sadly, that list appears to include the people in the factory who assemble the cars Link to comment Share on other sites More sharing options...
ralph Posted June 16, 2023 Author Share Posted June 16, 2023 Can confirm: motor runs!! Thanks to all for tips/pointers on this. Link to comment Share on other sites More sharing options...
KillerB Posted June 17, 2023 Share Posted June 17, 2023 Good show, Ralph! Glad to hear you solved the mystery. Seems we both suffered from factory assembly errors. On the upside, at least you’re super familiar with the wiring now. 😉 1 Link to comment Share on other sites More sharing options...
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