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P1653 fault code interesting stuff

6K views 7 replies 2 participants last post by  alfizta 
#1 · (Edited)
Hi dear alfisti! Trying to be quick on this one...

Today tried once more to investigate a permanent p1653, variator related fault, on my 156 1.8 TS M.Y.2000, Bosch M1.5.5, with tests below.
Steps 1) to 6) were also done on my older 146 1.6 TS M.Y.1997, Bosch M2.10.4, which is faultless, and passed all of them.

1) Checked variator solenoid resistance, 5 to 7 Ohm (10 Ohm on service manual, 33 Ohm on my 146)
2) Reset fault code with MES
3) Started the engine and let it warm a bit
4) Plugged a multimeter on solenoid terminals and checked voltage while accelerating, 0 V (about 14V on my 146)
5) Plugged the multimeter in series with the solenoid, checked current while accelerating, 0 A (about 0,8 A on my 146)
6) Fault code flashed on MES but no engine managment light
7) Fault code reset
8) Fitted a 12 Ohm/17 Watt resistor in series with solenoid
9) Repeated step 4), about 14V
10) Repeated step 5), about 0,8 A
11) No fault code

My guesses:
1) When solenoid has very low resistance, it draws too much current, ECU automatically detects this fault and shuts power down to the solenoid, fault code pops!
2) The 12 Ohm resistor forces to drop current, ECU lets power get to solenoid, no fault code.
3) Seems like the faulty part is the variator solenoid and not the camshaft sensor, which is surprisingly not as expensive as the solenoid (solenoid almost 400 euros here in Portugal!!!!!) but much more complicated to change.

My questions:
1) Can I drive the car this way, with the 12 Ohm resistor fitted?
2) Is the variator really working this way?
3) Should I trade my 156 solenoid with the one on my 146? Parts are different, but are compatible?
4) What could be causing this lower impedance? This part is usually very relliable.
 
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#3 · (Edited)
Update

1) Taken the solenoid off.
2) Plugged directly to battery and it poped out the metal piece beneath, so it works, and now drawing just 1 A of current. Resistance raised to 12 Ohms ???? That doesn't make much sense...
3) Plugged with 12 Ohms resistor in series and it also worked but not as fast. Didn't checking current.
 
#4 ·
Update

1) Refited the variator solenoid
2) Test drive
3) No faults :)

Im guessing oil is filling where it shouldn't and causing a small shortcirtuit inside solenoid. Maybe it's a question of time for it to fail again and me finding a replace...
 
#5 ·
Resistance got lower again to 6 Ohms, p1653 poped again.
Might not be oil filling in the wrong place, cause oil has very low electric conductivity.
As soon it is removed resitance rises to 12 Ohms again and actuator works with 12V power :confused:
Can't understand this lowering in resistance...
Cleaned, isolated some metal parts of the actuator, and refitted again.
Update in a few days...
 
#6 ·
Just a thought... Could it be that as the solenoid warms, the coil driving it is expanding slightly from the heat? Couple that with cracked insulation as you get adjacent loops of the coil touching each other, it will effectively reduce the resistance. Cool down and the loops separate again as things contract causing the rise in resistance. Might be way off the mark, but just a thought?
 
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