TCS/ABS/Climate non-functional.. I humbly request help in this embarrassing situation

[shadetree]

Unfortunately this post is coming even before my introduction... Frankly because I don't even have the NSX yet.
Backstory: I have made a commitment to a local independent seller to buy his NSX. After securing funding I allowed myself the opportunity to take it for a test drive. For piece of mind, I wanted to also perform a compression check before handing over any cash. I called my preferred NSX mechanic, but he's booked solid for a week or two, so I decided to take the job upon myself after reading a few articles here. I have the tools and have done it on plenty of B/D series, so that makes me a mechanic, right? Right...
Where I probably messed up: Coil packs dangling haphazardly while I had the owner crank 'er over checking compression. My current working theory is that a coil pack shorted into the wiring harness or similar...
Symptoms: After putting it all back together, Traction control/ABS systems are non-functional with lights showing on the dash. Climate Control is non-functional. The lights on the knobs are on but that's about it. Car runs and drives just fine otherwise.
Troubleshooting: All fuses in the main three fuse-boxes have been checked for continuity. The seller says they're all good, which in my mind means something was shorted or fried. I am hoping someone familiar with these systems to be able to provide an "easy" solution if there was one... In the meantime I'm starting to pour over the wiring diagrams and I'll get back over there tomorrow to troubleshoot further. I'll begin by trying to find a relay or circuit these two systems have in common.

The owner has shown more grace than I deserve in this situation, and I'd really like to get him back on the road this weekend for one last road trip before he hands over the keys to my very expensive "project car" (at this point). Thanks to the community for any help they are able to provide. This wasn't my preferred method of learning how to properly do a compression check.

- - - Updated - - -

I've come to the conclusion these systems cannot be related. I've probably sent an extreme amount of voltage through to a few systems and damaged some of the more sensitive ones. I'll start by trying to track down a TCS computer tomorrow. Climate control can wait for now. Hopefully an internal fuse or individual component I can replace or something... Further suggestions welcome.

 

[ftuhy]

It might not make too much of a difference in troubleshooting, but
Year?
Mods? (including aftermarket alarm, stereo, etc)

 

[shadetree]

It might not make too much of a difference in troubleshooting, but
Year?
Mods? (including aftermarket alarm, stereo, etc)

1993

Aftermarket alarm and stereo (both work). When I get back to the car tonight I plan on checking the power mirrors, rear defrost, and cooling fan for functionality based on this post:

http://www.nsxprime.com/forum/showt...oming-on-why?p=1528138&viewfull=1#post1528138

and double-checking the fuses.

Already ordered a TCS control unit but I'm going to try to find one locally as well so I can try swapping it tonight. I'll also pull any codes.

Thanks.

 

[Old Guy]

The 'seller said they are all good' - does that mean you actually checked the fuses or are just relying on the seller's assertion that they are good? I would check.

The CCU lighting gets its supply off of a separate circuit so the lighting can work even if the supply to the CCU is dead. The CCU and ABS share at least one common fuse, the #4 15 A. The ABS control unit has an inspection connector on it. The supply off of the #4 fuse is brought out to the inspection connector so you should be able to test to see whether you have 12v to the ABS control unit - if you can find the inspection connector. You will have to check the service manual to find its location. The TCS does not appear to share a common supply so I don't know what the problem is there.

Do you know that all of this stuff worked before the 'incident'?

 

[shadetree]

The 'seller said they are all good' - does that mean you actually checked the fuses or are just relying on the seller's assertion that they are good? I would check.

The CCU lighting gets its supply off of a separate circuit so the lighting can work even if the supply to the CCU is dead. The CCU and ABS share at least one common fuse, the #4 15 A. The ABS control unit has an inspection connector on it. The supply off of the #4 fuse is brought out to the inspection connector so you should be able to test to see whether you have 12v to the ABS control unit - if you can find the inspection connector. You will have to check the service manual to find its location. The TCS does not appear to share a common supply so I don't know what the problem is there.

Do you know that all of this stuff worked before the 'incident'?

Thank you for the replies.

Seller was the one under the dash with the multimeter. We were checking for basic continuity only. I'll pull the #4 and make sure nothing is loose and double check them all tonight. I've also located a TCS unit locally to swap out as a possible cause of the TCS system malfunction.

When you say inspection connector, are you talking about the one in the passenger footwell, or a connector specifically for the ABS system? EDIT: I see it's a separate connector. Unfortunately that diagram is incomplete in the manual I'm looking at. I'll check some other versions.

It's unfortunate the electronically available versions of the manual aren't searchable. I'll have to change that...

I did sit in for a test drive last week, and the A/C was on full blast. There were also no ABS/TCS lights on so I'm inclined to believe the seller and accept responsibility.

I spoke with the local NSX mechanic who I trust. He was in disbelief that the coil packs would have been able to cause such damage, but in my mind it's pretty feasible.

 

[Old Guy]

Correct - separate from the service check connector. Its a 6 terminal connector that the 91-92 service manual says is under the glove box on the opposite side of the service check connector. The TCS has connections to the ABS unit control unit, probably for the wheel speed sensors. If the TCS is not getting a signal from the ABS control unit that could be the reason why you have a TCS failure indication.

When you did the compression test, did you unplug the coil packs and remove the sparkplug and coil packs or just pull the coil pack off and let it hang down? If you did the latter, I really struggle with how the operation of the coil would damage the systems that are inoperative. More likely to damage the coil because of internal flashover because of the higher secondary voltage when the plug isn't connected. Perhaps when you were tugging on the coil wires, you jiggled some wiring that was already compromised causing it to short out.

As a note, I have never felt compelled to do a compression check on my NSX; however, whenever I have done it on my other hobby vehicles, I make a habit to disable the fuel injection and ignition system(s) when I do it by pulling the fuse(s) that supply them. If you don't do that, every time you engage the starter to check compression on a cylinder, the fuel injection gives a priming pulse and basic cranking pulses to the injectors which just ends up with un burnt fuel in the cylinders. Some fuel exits out the exhaust port; however, some may end up washing down the cylinder walls. It also avoids the risk of zapping yourself on a sparkplug wire if you happen to get too close to it while doing the test.

 

[shadetree]

Thanks again for the reply... Mystery solved. When I had the owner pull the fuel pump fuse, he unplugged #4 at some point and put it back in #3 ... Glad it wasn't on me, and I appreciate your time.

Now to unload the TCS units I purchased for troubleshooting...