QuestionQUESTION: I've been having some problems with my speed dial indicator on my car where the dial goes crazy especially when it's warmed up fully or when I put the blower motor or use the power windows etc.
I know that the speed sensors on the transmission send signals to the TCM, PCM and the BCM picks up the signal via the two bus wires then sends it to the cluster assembly via the bus.
Anyways I've tried changing the comps,cluster assembly, tried 3 dif sets of transmission speed sensors , tried new grounds and new wiring and changed the bus wiring etc.
My thought is it's a bad wire due to when I move or tug on the main harness under the hood by the power centre and TCM it will cause my trip meter and mileage counter to move even when car is sitting at a light.Plus at times it seems the speed indicator acts up less when the harness is moved but still now a days even with the engine cold started the speed indicator goes haywire , especially if the blower motor etc is on.
Could a sensor like the crankshaft sensor or cam sensor or o2 sensor or knock sensor be acting up and causing the sensor ground wire that goes to all the sensors have some kind of feed back via the ground or bus system?I've noticed if the engine is real hot the problem gets worse and at times at stop lights regardless how warm the engine is it will buck or kick or hesitate.
Last thing is why I asked about the sensors besides the ground signal is bec my car seems to not idle as well lately and it takes longer to start up,plus at times it gets less gas mileage.I've changed , plugs , wires , coil pack.
Any ideas or feed back would be much appreciated and thank you in advance.
ANSWER: Hi Bob,
Have you checked the engine grounds? The PCM grounds near the right headlamp and the battery grounds are on the left front of the engine and at the left front frame rail. The other possibility for the poor idle is that your egr valve is sticking slightly ajar, so try spraying some WD-40 on the stem where it enters the valve body and then move it back and forth with the tip of a screwdriver inserted into the slot of the stem. Make sure that it closes to a dead stop via the internal spring-action.
Roland
PS I found this in the 'pool' to which Kevin had referred it.
---------- FOLLOW-UP ----------
QUESTION: Hi Roland and yes I made new grounds for the TCM and I've tested the PCM grounds and they were all had solid ground signals.
It's funny bec most of the time when I check and compare fuel consumption I'am getting 28 miles per gal but at times I'am getting poor mileage?
Do you know what resistance readings I should get from the Crankshaft, cam and knock sensors?
By the way I tried to reply to last nights question but it said I had maxed out my replies.
ANSWER: Hi Bob,
The cam and crank sensors are tested via their voltage behavior, not their resistance. When you turn the engine by hand (ratchet on crank pulley bolt) it will show a pulse in voltage, between 5v and 0.3v as measured between the signal and sensor ground wires, several times per revolution, of course with the ignition key in the 'run' position. But if the engine is running I would suspect that you will find this pulsing to be present. When they fail, they usually stop pulsing when they get warm, then cool and may work again, but finally they fail entirely. The knock sensors electronics are not something I have info about but I doubt that would be a cause of your problem. The manual says the the crystal in the sensor puts out a voltage which increases as the knock level increases and sends that voltage to the pcm for action (retarding the spark).
Roland
PS There is a limit to the number of 'follow-ups' per question.
---------- FOLLOW-UP ----------
QUESTION: Yes that's true those clusters have circuit board problems but any soldered board will do that especially after 10 years due to the ozone but I even took one of the 3 clusters and soldered many bad soldering connections and still no difference.
The harness that acts up is the main one under the hood that goes from the PCM to the TCM and runs back into the car.I suspect that a wire or wires are frayed or melted or damaged or bare some place in that harness.See what also happened one night I was switching from the low beams to high beams and I noticed the headlights went super bright then later I noticed the DRL running lights don't work anymore and the fuse for the DRL was melted in the PDC. That's one reason I replaced the multi function switch wiring.
You ever seen this problem? I go to turn on the wipers and they don't come on unless on high , and when you push the washer pump switch the fluid comes out via pump but the wipers don't come on at all.But when I test the wiring the BCM is getting power from the pump switch , the BCM is giving out power to the wiper relay too.The book says if the wiring is okay then it's the BCM but I've 4 BCM's and none of them make a difference.I believe the wiper park sensor is causing this problem?
AnswerIt sounds suspicious about the wiring harness. On the wipers, if the low-hi and the intermittent relays have the same part number I would try switching them to see if the problem changes. If it does then one of the relays has a bad internal contact. If things stay the same, then we have to think some more.
