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Speedometer stops working in Neutral...

Booba5185

Booba5185

New member
Is this normal? I'd think not...I'm driving down the road at 40 MPH, I shift into neutral, and speedometer drops to 0. Anyone ever had this problem? Everything else works fine except for my ABS and Traction control.
 


I'm having problems with my ABS and TCS am I'm wondering if this is related. I will be getting the codes pulled on the ABS\TCS issue if needed, but it'd be nice if this ended up being the issue.
 
Just a guess, but the ABS/TCS problem might be caused by a bad VSS in the wheel hub. Vehicle Speed Sensor. I believe there is one in the transmission as well which is why your speedometer works while driving, just not in neutral.
 
All 4 bearing have been replaced and tested good, at the EBTCM plug. I found that the PO stuff a paper towel under the key release, and purple wire with a white stipre was disconnected at the gear selector. I've fixed it, just haven't put everything back together yet, so we'll see if that is the cause of my problem.
 


Bump? Does anyone know how the speedo circuit works? In neutral does it receive it's signal from the EBTCM or something else?
 
Thanks for the reply, I thought the same thing at first, but my HUD drops to 0 at the same time. This weekend I'm going to spend quite a bit of time trying to find out more about the speedo circuit itself. Main question to answer is where does the speedo get it's signal when the transmission is in neutral? the EBTCM? the VSS? something else???
 
Its not any help but I have a 2000 white gtp and when I shift into nuetral while cruising my gas gauge drops to empty. Even the dic will say 0 miles but put it back in drive and it goes back up
 
I did some research, and there are quite a few connections between the PCM and the speedometer, along with a lot of connections in general everywhere, lol. I'm gonna tear into the dash a bit today to clean connections, trace wires, etc. just to get a better idea of what is going on in there...
 


Check battery terminal cables.. tis the season.. cold weather will make them not give 100% strength... and also itwouldnt hurt to start thinking about a new ground wire system.. from your battery get one of the side post aftermarket battery post nuts.. and ground from chassis to the battery.. and from chassis to the engine... giving the engine a better return path helps everything electrically.
 
Both of my gp's did the same thing, got the ebcm fixed on my gold one,fixed my trac,abs,and speedo.However,my red gtp does not have a bad ebcm,but it still has the speedo issue.
 
I've been tracing the BTSI problem and found a bad ignition switch, so I'm replacing it and seeing what happens from there.
 
Robxstone said:
Check battery terminal cables.. tis the season.. cold weather will make them not give 100% strength... and also itwouldnt hurt to start thinking about a new ground wire system.. from your battery get one of the side post aftermarket battery post nuts.. and ground from chassis to the battery.. and from chassis to the engine... giving the engine a better return path helps everything electrically.
Click to expand...
Engine has only been installed since August, and I've cleaned, replaced, and enlarged all grounds. TCS light and ABS lights have been on since I've owned the car.
 
Booba5185 said:
Bump? Does anyone know how the speedo circuit works? In neutral does it receive it's signal from the EBTCM or something else?
Click to expand...
the vss is generated from the output speed sensor in the trans. the signal from the sensor goes to the pcm. The signal is converted by the pcm to serial data and is sent to the ipc via the serial data lines. the ipc then converts this signal to a speedometer reading. The wheel speed sensors siganals are not used for speedometer function.
The speedometer will default to zero anytime a fault exists in any of the parts used to generate/display the vehicle speed.
 


Awesome, thank you. I'm thinking this BTSI issue might be the cause of the speedo problem, we'll find out tomorrow when I put the new one in.
 
BTSI: Brake Transmission Shift Interlock. The BTSI solenoid is only a solenoid that allows you to remove the key when you turn the car off. It's a solenoid in the steering column that when inoperable, you can stick your finger up under the trim and manually push to allow the key to come out. The PO stuffed a paper towel into the trim so it would always allow the key to come out... The BTSI itself wouldn't cause the issue with the speedometer, I know this. Troubleshooting the BTSI problem lead me to find out that the red/white stripe wire on my ignition switch was not getting +12V like it should. I'm still up in the air on what all this red\white wire powers, because the schematic I have is wrong. It says that there are 2 red wires, when one has a white stripe on it. The pin number in the schematic is correct and all, but the wire color isn't right.

I'll be investigating more don't get me wrong, but I'm sure this is a major problem. The BTSI thing is just how I stumbled onto it.
 
its is labelled wrong. the red/white wire connector 201 pin d5 is a fused battery feed for the ign main 1 maxi fuse 40amp. this feeds the ign switch which feeds the btsi fuse.
 
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