QuestionQUESTION: Rechecked the relays.... and even bench tested them.... fuel pump relay, asd relay, and starter relay are all good.
when turning over the ignition the relay clicks and 85 and 86 are positive for power for a split second.... 87a while in the run position shows power. still no crank unless doing a bypass from 30 to 87..... when doing the bypass the starter motor turns over even when no key in the ignition.
Could there be something else in the wiring schematic that can explain the no crank? There is also a NO BUS displayed in the gauges when trying to start.... is the issue a sentry system not recognizing the keys ..... or just not talking to the pcm or ecm that is keeping the car from cranking?
ANSWER: Hi Darren,
As I explained earlier the shop manual does not label the pins of the socket as you are using the numbers. Here is what I am assuming are the pin number positions of the socket:
30
87
85 87a 86
Is that correct...do we agree?
The starter relay will show 12v on pin 30 at all times.
Pin 85 should show 12v when the key is in the 'start' position, otherwise no voltage
Pin 86 should show no voltage (possibly except for a moment when first 85 begins to show 12v but as soon as the relay clicks it should show no voltage because it has been grounded by the pcm).
However, when you measure using the ohm-meter function, pin 86 should show a dead short to ground (O ohms) while you are in the start position and if the trans is in P or N. That dead short to ground is what causes the relay to close and stay closed. If it doesn't show a short to ground the relay will not stay closed, and then either the P/N safety switch is not working properly OR the PCM has intervened to stop the relay from closing, possibly because the theft system SKIM key is not valid and after 6 tries to start it and thus being quickly killed, so it is locked out until you get a valid skim key.
To check out the P/N safety switch I need to know whether your car has a separate pcm and tcm or does it have a single combined control unit. The wiring changed in mid-model year. If you have the single combined control unit it will have 4 plugs, if you have the separate pcm/tcm each will have 2 plugs. So let me know if you want to check out the P/N safety switch.
87a is not used and has nothing attached to its pin.
The 'no bus' means the cluster is not getting bus messages, but that may or may not mean the entire bus system is not working. Let us assume that it is working.
Roland
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QUESTION: 2 plugs per tcm and pcm
no power to 87....
I get power continually to 30, power to 87a when in on position, 85 and 86 when cranking over. 85 for split second and 86 as long as in the crank/start position.
But like I said no power to the 87, which is what you are having me jump to from 30 to get the starter to run.
The question should be is why is no power getting to pin 87...
Is there something communicating to make no power get to pin 87?
ANSWER: Are the numbers I showed you what you actually have? Could I have 85 and 86 reversed in my figure?
If so that would make sense to me because what I show as 85, the left pin, comes from the ignition switch and so should show 12 when in Start. I believe that 86, the right pin, should show 12v for a moment and then it should be grounded by the PCM which is what closes the relay switch and sends voltage from 30 to 87. See if that right pins shows a dead short to ground when you have key in the start position (as well as showing 0 volts).
As to the P/N switch in the transmission, you have the 'early build' and on that one check to be sure that pins 5 and 10 of the ranges sensor plug show a short to ground in P and N and that they show open (infinite ohms) in the other gear positions.
Roland
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---------- FOLLOW-UP ----------
starter relay
QUESTION: I double checked the power to the relay again, for the third time.
This time power noted to both 30 and 87 even with no key in ignition.
pin 85 and 86 only showed power in the crank position and did not turn off unless taken out of crank position.
The other day only pin 85 stayed on and 86 turned off within a split second.
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See if that right pins shows a dead short to ground when you have key in the start position (as well as showing 0 volts).
How do I prove a dead short to ground for 86... whic wire would I be testing at the PCM?
at no time is any power getting to 87.
AnswerHi Darren,
The fact that you are seeing different results from day to day causes me to believe either that there is something intermittent in the wiring or that the measurements that you are reporting to me are actually not identical from day to day.
A "dead short to ground" means that when you have your ohm reading selected that it show 0 ohms measured with the relay removed between pin 86 of the socket for that pin in nearby ground (i.e. the - post clamp of the battery). What does it show when the in "off" in "on" and in "start" with the P or N selected.
Have you checked the ohm reading of the trans mission range sensor pins at its socket? That may be why the no start.
Roland
PS Thanks for the image. It does indicate that my belief about the specific locations of the pin assignment in the socket were indeed reversed. But that doesn't change the above answer.
