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Electrical problem; need expert opinion but will settle for a wild guess.

Joined
10 November 2002
Messages
1,124
Turned out to be the NM Speed Sensor - Solved! by Larryb

I was driving to work down the interstate when the power steering suddenly clicked off and the EPS warning light came on. Soon, the speedometer started bouncing around. When the speedo started bouncing around this apparently pissed off the automatic transmission because the "D" light in the dash cluster started blinking. Finally, as I was making a left turn, a puff of smoke rolls out from under the dash underneath the steering column. I was ready to bail onto the shoulder and let her burn, but it didn't catch fire. I made it to work, and after parking restarted the car. Everything except the EPS light seemed okay. That night, the car died right outside of work and I had to have a rollback take the car to the dealership. (I showed up at the dealership and they were still working in the service department at 1 am, which is nice because I can drop off my car in the afternoon and pick it up at midnight, which matches my work schedule.)

So the next day they call with an estimate of $350 for a new ignition wiring harness. The old one was very poorly wired together due to an added and removed aftermarket alarm system, before I owned the car. I was like, no problem, go ahead and do the 90k service and timing belt/water pump also as the car had aprox. 88,400 miles on it.

So after a coupla days they call back and tell me that apparently the crank pulley had not been properly tightly bolted to the crank when the timing belt was replaced before I owned the car, and that the wiggling crank pulley had worn off the portion of the crank lobe where the shear pin is located. They advise me that they are having a machinist look at the crank for an estimated $600 repair, or they will have to replace the crank for $5700 (gulp).

So the machinist decides he can fix it, for a revised estimate of $750. Go ahead. A lot better than a $5700 crankshaft or worse, a blown engine. They end up drilling two holes in the end of the crank and installing two pins in place of the single shear pin. I am completely satisified with this outcome.

So finally the service rep calls and ends up quoting me a final figure of over FOUR THOUSAND DOLLARS for the work, which included the crankshaft mod, timing belt, water pump, ignition harness, 90k service, right turn signal lense, new tow hook cover, and an oem stereo install (I provided the radio, which incidentally I purchased on NSXPrime; thanks JaySpec7.) This is clearly a premium price but that isn't really the problem.

The problem is, when I picked up the car, the EPS light was still on! I tried resetting it myself four different times and the EPS wouldn't come back. The previous times I have reset it, it has always started working again. This time it seems like the EPS isn't getting a power feed at all, but the speedo and D-light are normal. So I take the car back in and tell the service rep that the EPS wasn't working, and that it had been working before the electrical problems that day, so could they fix it? Maybe the power feed was inadvertently overlooked or something? The rep tells me that he knows it isn't working, that the car had been there before for an EPS diagnosis. Which is true, they spent several hours troubleshooting an occasional EPS failure a coupla years ago. But now the EPS isn't working at all, not just an occasional dropout months apart like before. Also, what totally baffles me is that the tech acted like it was normal to return a customer's car with something not working. Why would I bring it in if I didn't want everything fixed? I never asked to just repair certain things. And before I picked the car up, he never mentioned that, oh by the way, the EPS isn't working. If I would've known that I would've just told him to keep it.

Finally I become exasperated with our perplexing discussion and tell him not to do anything to it; I will come and pick the car up. So I pick the car up, and the EPS is working normally. Electrical gremlins doing their dastardly work. But on the way home from the dealership, the EPS light comes on, the speedo dies temporarily, and the D-light on the tranny starts flashing. Sigh. So I am asking 'Prime members for advice. The automatic transmission shifts normal, seems normal, etc. Any thoughts, like the grounding strap or speedometer pick up or transmission lash or anything that comes to mind? Again, I emphasize that I am not upset about the bill, and feel that the work that was performed is satisfactory, and that the crank repair approaches being ingenious. I just want to rid myself of the electrical gremlins.

At least I have tunes! BrianK's sub and speaker repair are performing admirably (no popping and cracking) with the pathetic oem radio. And I threw away my harmonica. My lips were getting really chapped...
 
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I would look at two things: Speed Sensor and Main Relay. See if you can borrow a speed sensor from a working car. Main Relay is about $50 so just get one:). Speed Sensor is around $200

HTH,
LarryB
 
I had the main relay problem three years ago and am familiar with the symptoms of that problem. The engine doesn't cut out like with a main relay problem; only the aforementioned systems are affected. I resoldered the main relay then and don't think it is the culprit now. I will look into the speed sensor issue, which may cure the speedo and angry D-light problem. The speedo only starts dropping out after the EPS light goes on, which in turn upsets the automatic transmission which then narcs on the speedo. But all three seem closely tied together as they all go in sequence; EPS light followed by speedo followed by tranny light. It seems like a momentary break in electrical power causes the EPS to drop out which is then followed closely by the speedo dropping out which is then followed closely by the D-light flashing to "tell" on the speedo. The tranny seems otherwise fine.

It still seems like a wiring/power feed issue as the trio all come on at once, but I will have a look at the speed sensor.

Thank you for the suggestions.
 
I reviewed the code list in the FAQ. I don't see anything that seems pertinent, although I will check anyway to see if it is throwing any codes.

Thank you for the suggestion.
 
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The speed senor is in common with all these symptoms.

EPS, auto trans, and speedo ALL use it:).

HTH,
LarryB
 
I researched the speed sensor issue and in a previous post an automatic NSX owner mentions the exact symptoms I have and goes on to say that replacing the speed sensor cured all of the problems. Thanks for the info! The dealership would've done a coupla thousand dollars worth of work and it still would not have been fixed! Now I need to check the connector for tightness, or get a new speed sensor.
 
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Searched online for a speed sensor just to see what it looks like and to post for anyone who looks at this thread again. Found this one at Autopartswarehouse.com, on sale for $105.11. Is this an oem part? It doesn't have an Acura-style part number, but I believe it is applicable to other Acuras and maybe other Hondas as well, so maybe it is still cost-effective to produce this as an aftermarket part. I would prefer an oem part.
 

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Seems too cheap to me. If it had an OEM part number and was about $150 I would go for it. JMO.

HTH,
LarryB
 
Dropped the car at the dealership tonight with specific instructions: 1-Pull the error codes from the OBD1. 2-Replace the NM speed sensor. 3-Check for loose connections, or open or shorted circuits.

Hopefully this will be enough to cure it...
 
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Picked up the car tonight at 11:45 pm (gotta love those hours). When I drove it there the EPS light was on, the speedo started dropping out, the D-light on the automatic transmission started flashing, the TCS dropped out on the way, and the Check Engine Light came on. After replacing the speed sensor, it all went away. The error code (indicating a faulty speed sensor) and wiring connections were checked. But other than the speed sensor, no other actual repairs were made. The speed sensor sure affects a lot of things. Total tab was $460 out the door.

The car seems to be fine now. Thanks again for pointing out the likely problem.
 
In gratitude for valuable knowledge received, I have made a cash contribution via Paypal to NSXPrime in honor of Larry Bastanza. I also nominate Larry for a new custom user title, "NSXprime.com Legend", acknowledging him for extraordinary personal contributions to the worldwide NSX community.
 
Jett said:
Picked up the car tonight at 11:45 pm (gotta love those hours). When I drove it there the EPS light was on, the speedo started dropping out, the D-light on the automatic transmission started flashing, the TCS dropped out on the way, and the Check Engine Light came on. After replacing the speed sensor, it all went away. The error code (indicating a faulty speed sensor) and wiring connections were checked. But other than the speed sensor, no other actual repairs were made. The speed sensor sure affects a lot of things. Total tab was $460 out the door.

The car seems to be fine now. Thanks again for pointing out the likely problem.
What was the break down for parts/labor, if you don't mind sharing. :smile:
 
The following is an itemized breakdown for the speed sensor portion of the work. Prices reflect premium Acura rates. (I will edit this post and break out the cost of the entire ordeal when I figure out where I put the other invoice.) DIY'ers should be able to do the speed sensor replacement for less than half this price, or even at less than 1/4 the price if you buy the aftermarket speed sensor. I don't have the time, place, talent, patience, or toolbox to do the job myself.

Scan system for codes $ 85.00
Speed Sensor - 211.77
Labor to replace speed sensor - 140.22
Environmental supplies & waste removal - 11.25
Tax (aprox. 2.5%, everything wasn't taxed) - 11.16
_________
Total for speed sensor replacement $ 459.40


One last thank you to LarryB. It was nice to walk into the service department the last time and be able to say "Scan the OBD1, replace the main speed sensor, and check for loose wires." Direct and to the point. The service rep looked at me like maybe I gave the appearance that I actually knew what I was talking about. For a second anyway.

I would like to point out that I am not upset at the service department. Although expensive, the work they did seems first rate. I would have hoped for more knowledgable troubleshooting, but I don't think they were trying to rip me off or anything. I will use them again. I will just try and walk in more knowledgable the next time. I also point out that if you are a capable mechanic, you can save a boatload of money doing work yourself that isn't technically that difficult. You don't pay for the work insomuch as you pay for the knowledge. Troubleshootin' is hard, parts swappin' is relatively easy once you figure out which parts to swap.

I drove the car to work today, a 150-mile round trip including a side trip I took on the way home. As I cruised downtown DC, all the hotties were out on a beautiful fall Friday night and I could hear the guys on the sidewalk saying "Hey, check it out, NSX" to their friends. (I wish I could get the same attention from the chicks that the car gets from the guys.) All systems seemed to be tight, and the car was performing great. It is in top notch mechanical condition now and although not cosmetically perfect it still looks pretty nice for a '94.
 
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Jett,

Thank you for your kind words. The donation to Prime is a great idea, and is much appreciated. Glad your car is back to normal:).

Regards,
LarryB
 
Jett said:
...I also nominate Larry for a new custom user title, "NSXprime.com Legend", acknowledging him for extraordinary personal contributions to the worldwide NSX community.
Larry was already deservedly acknowledged by the collective members as the number one contributor of helpful knowledge in a prior pilot voting scheme that was subsequently scrapped. He was officially "the King" of the guru's, not just subjective opinion.
We're lucky to have him for all his incredible advice and for his time that he is willing to share it.
 
wow!

it doesnt take 2 hours to change out the speed sensor.. i did one in an auto in the driveway on stands. total time less than 30 mins.

but stealerships charge book rate, and not actual... maybe thats why....

glad to see you got it fixed. I was suspecting the Speed sensor when i first read this post. i dont prime often enuf anymore, but Larry came to the rescue again!
 
Thank you for posting this thread. Found the answer for my bouncing speedo!

I'm curious if this will cure my "5th gear engine hesitation", which is like the engine is only firing on less cylinders when under load.
 
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