Previous symptoms over the last two months: Speedometer quit working Hard downshifts when slowing down ..... I was driving at 60mph, low on fuel, transmission fluid level was within guidelines. when the Transmission "slipped" severely, tachometer bounced way up and down multiple times, engine light came on and the car died..... and stayed dead. The car now has no spark, no fuel pressure, turns over but will not even try to start. When key is on, there is a buzzing sound coming from the PCM..... I Replaced the PCM .... but the symptoms are the same.... Including the buzzing.... All ground connections (firewall and under driver seat) seem good. Purchased code reader but there are no codes. At a total loss for ideas..... Help!
It is possible that the ASD (Auto Shut Down Relay) has gone bad. The ASD provides signal/power to the fuel pump and to the engine coils. It is usually located in the fuse box under the hood. The fuse box cover should indicate it's location. The ASD is often a square relay and there may other such relays that look the same and have the same configuration of pins in the fuse box. If so, one may be the horn relay. Often relocating one of the other nonessential relays (horn relay) to the ASD position will allow the engine to start. If so, replace the old ASD relay.
SOURCE: 1998 Jeep Wrangler Sport codes P0121 and P0122
did you check voltage to sensors if you need help with proedure, contact me, or you may try patrs houses on line in how to section.
SOURCE: 2005 PT Cruiser P0700, P0720, P0731 stuck in low and Speedometer
YOU HAVE A DEFECTIVE OUTPUT SPEED SENSOR ON TRANSMISSION..ABOUT 40 BUCKS,DEALER PART..SCREWS INTO FRONT OF TRANS..NEAR LEFT INNER FENDER,YOU MIGHT WANT A MECHANIC TO REPLACE..
SOURCE: 2001 Chevy Malibu, 89,000 miles, 3.1 engine, won't start
CLICK HERE for the injector schematic.
CLICK HERE for the Ignition schematic.
Since the PCM uses info gatheres from the crank and cam sensors to calculate ignition - and there are no OBD codes - in all likelihood, the PCM itself is bad.
The Ignition Module, also transmits to the PCM.
It appears after all your testing - that the PCM is at fault.
It does not error report on itself (unfortunately).
The ignition timing is controlled by the Powertrain Control Module (PCM). No adjustment is necessary (distributorless ignition) or possible.
Please see the following....
The ignition timing is controlled by the Powertrain Control Module (PCM). No adjustment is necessary or possible.
The engines covered by this manual are equipped with distributorless ignitions, ignition timing is controlled by the Powertrain Control Module (PCM), as applicable. No adjustments are possible. If ignition timing is not within specification, there is a fault in the engine control system. Diagnose and repair the problem as necessary.
Ignition timing is the measurement, in degrees of crankshaft rotation, of the point at which the spark plugs fire in each of the cylinders. It is measured in degrees before or after Top Dead Center (TDC) of the compression stroke.
Ideally, the air/fuel mixture in the cylinder will be ignited by the spark plug just as the piston passes TDC of the compression stroke. If this happens, the piston will be at the beginning of the power stroke just as the compressed and ignited air/fuel mixture forces the piston down and turns the crankshaft. Because it takes a fraction of a second for the spark plug to ignite the mixture in the cylinder, the spark plug must fire a little before the piston reaches TDC. Otherwise, the mixture will not be completely ignited as the piston passes TDC and the full power of the explosion will not be used by the engine.
The timing measurement is given in degrees of crankshaft rotation before the piston reaches TDC (BTDC). If the setting for the ignition timing is 10 BTDC, each spark plug must fire 10 degrees before each piston reaches TDC. This only holds true, however, when the engine is at idle speed. The combustion process must be complete by 23° ATDC to maintain proper engine performance, fuel mileage, and low emissions.
As the engine speed increases, the pistons go faster. The spark plugs have to ignite the fuel even sooner if it is to be completely ignited when the piston reaches TDC. Spark timing changes are accomplished electronically by the engine and ignition control computers.
If the ignition is set too far advanced (BTDC), the ignition and expansion of the fuel in the cylinder will occur too soon and tend to force the piston down while it is still traveling up. This causes pre ignition or -knocking and pinging-. If the ignition spark is set too far retarded, or after TDC (ATDC), the piston will have already started on its way down when the fuel is ignited. The piston will be forced down for only a portion of its travel, resulting in poor engine performance and lack of power.
Timing marks or scales can be found on the rim of the crankshaft pulley and the timing cover. The marks on the pulley correspond to the position of the piston in the No. 1 cylinder. A stroboscopic (dynamic) timing light is hooked onto the No. 1 cylinder spark plug wire (2.2L engine only, on the 2.4L engines, special adapters are needed) . Every time the spark plug fires, the timing light flashes. By aiming the light at the timing marks while the engine is running, the exact position of the piston within the cylinder can be easily read (the flash of light makes the mark on the pulley appear to be standing still). Proper timing is indicated when the mark and scale are in specified alignment.
WARNING
When checking timing with the engine running, take care not to get the timing light wires tangled in the fan blades and/or drive belts.
The engines covered by this manual are equipped with distributorless ignitions, ignition timing is controlled by the Powertrain Control Module (PCM), as applicable. No adjustments are possible. If ignition timing is not within specification, there is a fault in the engine control system. Diagnose and repair the problem as necessary.
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SOURCE: 1998 dodge grand caravan transmission slipping
A good place to start would be a fluid and filter change, and be sure you use proper (recommended) fluid. Then I would remove connectors to solenoids, modules etc, on transmission and clean them well with contact/electrical cleaner. Disconnect battery prior just for sake of safety & to make sure no circuits get shorted while doing it.Then give it a try, and see if any improvement. If still acting up, I'd spend a few bucks on at least having diagnosed by a knowledgeable technician at a dealership, or a transmission repair chain. Sometimes it can be a solenoid or speed sensor, or something not too expensive. Once you have proper diagnosis, then make your decision.
SOURCE: 1995 ford taurus no speedometer, abs light, won't shift correctly
speed sensor needs replaced
Hello
The
Engine and Automatic Transmission (not applicable to manual
transmissions) in this vehicles drive train are fully
electronically controlled by a computer called the PCM and TCM (Power
Train Control Module, Transmission Control Module). When a problem
like this or other drive-ability related problems occurs the computer
stores a record of the problem (there are of course some exceptions
to this, like the fuel pump, engine coolant temperature sensor and
MAF sensor for instance) in the form of a fault code in its memory,
to read these fault codes you must have the systems memory scanned
with a special tool. Once the fault code(s) are read you then must
perform the appropriate diagnostic testing to find and resolve the
problem(s) DO NOT REPLACE ANY PARTS UNTIL A TRAINED
TECHNICAIN HAS DIAGNOSED THE PROBLEM TO AVOID SPENDING YOUR HARD
EARNED MONEY ON PARTS THAT MAY NOT CORRECT THE PROBLEM. Also always
check fuel pressure for correct spec for your make and engine type.
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