Looking for ideas on what could cause a huge voltage drop to the starter.

I just bought a second 2004 R50 that wasn't running to see if we can bring it back to life for my son. I was told the car wouldn't go into 3rd gear (CVT) and that it won't crank now (the previous owner doesn't think they are related--has been sitting for a couple of years). They believe it is a security (immbolizer) issue.

I tried to jump pins 1 and 2 on the immobilizer to see what my voltages are with the ignition switch turned. On pin 2 I have 12.6 volts...on pin 1 it showed only 1 volt (both should be 12.6 and crank the engine).

I took the ignition wire off the starter solenoid and attempted again, now I have 12.6v on the starter wire. Put the wire back on the starter I only have 1volt.

Any ideas as to why I would have such a voltage drop that wouldn't allow 12 volts to turn the starter? I pulled the starter yesterday and took to 2 shops and both tested the starter good. The constant + side of the starter is 12.6 and I have tried with the same results to leave the alternator wire connected and removed.

 

Checked continuity on starter housing with engine, frame, mounting bolt, engine ground strap and all tested good.

Anybody have a good R50/R53 ignition wiring diagram?

 

PM me with an email address and I'll send you the relevant section (PDF) from my Bentley manual.

 

Thanks, I got it to crank tonight!
I was talking with RPMmotors about the EWS and they suggested issue was with the ignition switch. Swapped with another known, good switch and I got it to crank (on a weakened battery). I'll try again after getting the battery recharged!

After I get a start, I'll change all fluids (been sitting for a while). I was told the car wouldn't shift into 3rd gear (CVT). I'll use INPA to readapt the CVT and clutch ratio before putting it on the road too.

 

Keep us posted. I drive an 04 R50 CVT and it has recently begun misbehaving. No manual mode difference. Slow starts. Generally I am in 1 and 2, up to 50mph for the short commute. Shifter assembly sends all the proper positions to the ECU and there are no faults besides license plate lamp bulb outage. I managed the learning sw reset trough the cluster to no effect. Adaptations are next once I get the correct tool.

 

It was definitely the ignition switch...starts every time now.

My issue now is with finding the EP faults. Errors I was getting with ISTA-D were ABS and brake light switch along with 0721 for rotational speed sensor. I replaced ABS sensors and brake light switch...no errors there now.

Previously replaced Start Inhibitor (Neutral/Safety) and CVT Filter/gasket & Fluid so definitely needs adaptation. I replaced the rotational speed sensor (easy to replace with battery box removed). I'm running in xD for adaptation but the car errors to EP and the 0721 fault keeps returning. Today i noticed a few nicks with bare wire to the sensor and replaced with a similar connector from Autozone (Duralast 789). Ran again, same error. So, I ran new wire from the DME to the sensor (just brown/orange and black)...error again. I then thought possible bad ground. Ran the brown directly to body ground instead of through the computer...no error returned but I couldn't get the car over 30mph for adaptation. Will run through complete adaptation again and will let you know.

Letting the car rest to cool for attempting adaptation tomorrow evening...more to come!

 

I ordered a cable with INPA from Cable-Shack on ebay last year. I was able to get it loaded and ran the adaptation on my original 04 R50. Pretty easy process.
ISTA-D is a much better product for getting more detailed computer diagnosis and I was able to use the same cable.

 

Problem was definitely the ignition switch...on to the transmission problem now!

 

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