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Issue with High Boost CTSC Kit with AEM EMS

Joined
1 July 2011
Messages
219
Hello!

So I got bitten by the boost bug and I decided to buy a CTSC high boost kit from another member on the board. It came with a series 1 AEM EMS which was already tuned (figured it would be a good base map since my set up is similar). The install mostly went without a hitch per the instructions. The car starts and everything, but the speedo doesn't work. I've checked the VSS wire to the ECU; it's reading 12v. Not sure if it's the VSS, because I've replaced that recently, actually. I ordered a new one anyway which is on the way.

Everything in the engine bay is plugged in. I tried to use the factory ECU, but it won't start the car, I figured giving the car momentum with the factory ECU in the "on" position should at least read speed. No go.

I tried a diode to the VSS wire going into the ECU to see if there was some kind of negative feed back. Also nothing. Moved the jumper inside the AEM unit as suggested by the installation notes for the unit, but that didn't work either.

I've tried contacting AEM, almost sure they just don't give a shit about this unit anymore to provide feedback or support. Their forums had little information about if it could be the EMS or not.

I've checked all my fuses, tested all my grounds. I've never removed my cluster either, but I guess I can check there too. This whole thing is so strange to me.

Are there any fuse areas I may be missing?

I'm at wits end trying to figure out this issue! Any help or advice would be greatly appreciated.
 
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Could be the AEM box. One quick thing you can check is hooking up your AEM box to your computer to see if the ECU can read the VSS signal using the AEMPro software.
 
So small updated, hooked it up to the laptop, there was no vehicle speed reading.

I've already ordered another VSS, it's on the way -- so I'll replace that and see if it works afterwards.
 
Hello, just put the new VSS in. Did not work.

Odometer and Speedo still aren't working.

Is there a possibility it could be the AEM unit itself?
 
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I Am going from memory here so by all rights this could be wrong but I think the vss signal is buffered by the abs unit first then feeds the ECU and dash. I would have to look at the schematics again to confirm but maybe someone else knows for sure. Maybe check the abs fuses to make sure it is working. Again this is from memory and that goes as I get older.

Dave

- - - Updated - - -

Looked at the service manual. check for a blown fuse no.5 (10amp) in the dash fuse box, that supplies power to the speedo. There is also a fuse that supplies power to the speed sensor, Fuse no. 2 (15amp) in the dash fuse box.

Download the owners manual, there are several simple test with a meter to narrow this down.

Speed Sensor Test - Page 23-133
Speedo Troubleshooting - Page 23-131

Dave
 
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I Am going from memory here so by all rights this could be wrong but I think the vss signal is buffered by the abs unit first then feeds the ECU and dash. I would have to look at the schematics again to confirm but maybe someone else knows for sure. Maybe check the abs fuses to make sure it is working. Again this is from memory and that goes as I get older.

Dave

- - - Updated - - -

Looked at the service manual. check for a blown fuse no.5 (10amp) in the dash fuse box, that supplies power to the speedo. There is also a fuse that supplies power to the speed sensor, Fuse no. 2 (15amp) in the dash fuse box.

Download the owners manual, there are several simple test with a meter to narrow this down.

Speed Sensor Test - Page 23-133
Speedo Troubleshooting - Page 23-131

Dave

Thanks so much for the info! I'll check it as soon as I can! Much appreciated!
 
Sort of bad news -- I took my car to my buddy's shop to do my fuel pump and had them double check the fuses for me. He says that none of them are blown. Any other possible suggestions? I'm going to DL the service manual and take a look through it. This is driving me nuts!

Thank you for all the help so far, guys.

Edit:

Looking over the FSM, maybe I should check the grounding point on the Supercharger itself? The wire is so short though; where the hell would I ground it otherwise?
 
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Aside from your speedo issue, how does the car run? Curious which fuel pump you went with.

Just updating you -- car runs really the same as before. With headers and test pipes in, the clarity is a lot louder, but obviously haven't gotten on the throttle because VSS isn't working, and vtec isn't engaging. Fuel pump seems to work fine, though.

Edit:

Tried a new ground, nothing there. Could it be that the new VSS I bought is bad also? It was one from e-bay...where would you guys buy a VSS? I'll buy another one if it means my car working again...yeesh. Any way to test these things?
 
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SO. I think I may have figured out the issue, at least partly.

I measured the resistance in the VSS wire itself (not the G101 ground) and found that it was running something like 178ohms -- obviously too high, so I tapped the wire to a more stable ground. Blew my #2 fuse, so the car wouldn't start.

Now I'm sure that the reason the VSS isn't working is because the ground wire resistance is too high. I'm going to try to clip the wire and ground it elsewhere, and hopefully that'll fix my problem. I'll keep you posted.

fuse.JPG

Attached is the diagram that illustrates how these relate to each other.

- - - Updated - - -

OH MY GOD.

It was a bad ground. I regrounded the wires at the engine bay directly to G101 and everything is now working. So happy. Thanks for all the help guys!!
 
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