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CPS info (and something for Vince) Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Wed, 9 Feb 2005 17:55:31 Members do not see ads below this line. - Help Keep This Site Online - Signup |
There's been a lot of talk about Crank Position Sensors. I've done a little research.
Vince - code 12231 is No Engine RPM Pulses. Read on, and you'll see why that's a DI issue. The other code like this would be 12254.
There are two types of CPS. The Hall-effect CPS is used in the LH systems - up to 93 in the 9000, except for the 9000T, which went Trionic in '93. The hall-effect sensor is mounted behind the main pulley (harmonic balancer), and has three wires going up to a 4-pin connector under the intake manifold on the way to the DI computer. What? You didn't know there was a DI computer? Yes, it's mounted right next to the LH computer at the base of the windshield. The DI computer drives the DI cassette. The DI computer takes the signal from the Hall-effect CPS and produces a set of pulses. Those are the Engine RPM pulses. Those are sent from Pin 29 on the DI box to Pin 1 on the LH computer.
There is a shutter wheel mounted to the back of the main pulley, with three gaps.
Want an easy way to test this? Right by the Left Hand hood hinge there is a metal modification plate, and a black plastic oval cover. Pop it off it access the Test Connector. There is a 6 pin round connector. Pin 5 is closest to the windshield, and Pin 2 (ground) is farthest. Put a voltmeter on pin 5 (hi) and 2(lo). The voltage should be around 6 volts when the engine is cranking; it should be above 8 volts at idle. It's actually pulses, for those out there with an oscilloscope. Don't see that voltage? Then check the wiring. It may be the connector under the intake manifold. It may be a bad Hall effect. It could be a bad DI box. This is NOT the DI cassette.
If you see the right voltage at the test connector, check it at the LH box (pin 1). It may be a wiring problem.
The Trionic sensor is a different beast. First, it's located in a different place - it's stuck in the side of the block, down low by the crankshaft, near the transmission. There is a shutter wheel inside the block, but with 59 slots. And the sensor is NOT a hall-effect. It's a simple inductive pickup - essentially a coil of wire. It has a three wire connection, of which two are ground, and it goes directly to the Trionic control box. To test it, with the car off, pop the connector off the Trionic box. With an Ohmmeter, measure resistance between pins 41 and 67 - those are connected to the sensor. The resistance should be 540 +/- 55 ohms.
posted by 12.76.134...
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