The shielding is connected to ground - easy enough to find with a multimeter.
You can see that the shields on the wires are connected together through pin 3 on the connector and then go to ground at the DME.
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| Hits wall at 4000 rpm/limited performance - ref sensors? http://forums.tipec.net/viewtopic.php?f=25&t=23443 |
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| Author: | mikseymono [ Wed Aug 08, 2018 11:48 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
mikseymono wrote: Waylander wrote: the plugs are called Junior Timer Plugs or sometimes EV1 plugs they are available for not much money from Brandshatch Performance https://shopbhp.com/ I have replaced the Hall sensor plugs, Injector Plugs, Temp sensor Plug on my 968 with parts from here, https://shopbhp.com/products/tyco-amp-3 ... -and-seals https://shopbhp.com/products/amp-3-way- ... h-ev1-type Thanks...these look good! M Just arrived in post this morning...TBH a bit afraid of the current female plug wires as it is a moulded plug and can not see if there are three separate wires to go into the new female plug. There is also hardly any slack in the speed sensor cable...allowing for almost zero errors.....and what with my recent woes at the moment I am a bit reticent to give it a go...as currently she still goes! So, if I expose the female plug wires...will there be three wires? Thanks, M |
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| Author: | Waylander [ Wed Aug 08, 2018 9:14 pm ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Two wires and a shield Bit tight for space, careful examination may reveal a little slack |
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| Author: | mikseymono [ Wed Aug 08, 2018 9:22 pm ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Understand the two wires....nor sure on the shield...does this go to the third wire bit? |
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| Author: | Waylander [ Wed Aug 08, 2018 11:17 pm ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
It might not actually connect to anything, it’s a fine wire mesh that coats the two inner wires to provide an RF (radio frequency) block / shield The crank sensor is just a Hall effect sensor so only has two wires that carry signals the shield is to keep the signal clean and tidy |
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| Author: | mikseymono [ Thu Aug 09, 2018 7:54 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
I guess i will need to know for sure before I start splicing up my cable! I'll email the place I bought them from and see if they know for definate. Cheers, M |
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| Author: | Gryphon [ Thu Aug 09, 2018 8:39 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
The shielding is connected to ground - easy enough to find with a multimeter. You can see that the shields on the wires are connected together through pin 3 on the connector and then go to ground at the DME. |
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| Author: | mikseymono [ Thu Aug 09, 2018 8:53 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Thanks for this...on the reference mark sensor pin 3 is not labelled?! Is there a reason? Need to get my head round this wiring stuff as don't really fully understand TBH. How do you find ground with a multimeter?  Cheers, M |
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| Author: | Gryphon [ Thu Aug 09, 2018 9:05 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Pins are often unlabeled - or had tiny labels when new that don't survive the tests of time! Easiest way to find ground with the multimeter is the 'beep' continuity check setting. Good little explanation of it here: https://learn.sparkfun.com/tutorials/ho ... continuity Essentially it just checks whether there is an electrical connection between the two things you touch the probes to. In your case you want to find out which pin is connected to ground. Touch one probe to the -ve battery terminal - although pretty much any exposed metal in the engine bay should in theory be grounded - and the other probe to the pins. One of the outer pins should cause a beep - that will be pin 3. Test on the harness/DME side of the connector - the sensor side isn't connected to anything! If you can't get the probes into the sensors - I can't remember if the harness side is male or female - then you can get a pin or little bit of thin wire to push into the connector pin. |
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| Author: | mikseymono [ Thu Aug 09, 2018 9:11 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Fantastically explained! Will get to it..... Thank you, Michael |
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| Author: | mikseymono [ Thu Aug 09, 2018 10:19 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
So have found the earth wire/shield wire on both. Have checked continuity on both plugs...and now however much I wiggle/bend plug it gets constant continuity/beep. Does this mean it is probably OK? i.e if it ain't broke don't jigger with it.... Last week was definately more intermitent though. Thanks, M |
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| Author: | Waylander [ Thu Aug 09, 2018 11:23 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
the shield is connected to ground, so thats fine if it does not loose the bleep, its the two wires that connect to the DME computer that also need testing for breaks, I do believe you are over compensating for your little foray in to electrocution last week, as long as you connect the wires pin for pin in both connectors you will be fine, but do unplug the DME computer before you start, and the battery ! |
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| Author: | Matt749 [ Thu Aug 09, 2018 11:25 am ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Hi, From what you've said I think you are only checking the continuity of the screen around the signal cables but not the signal cables themselves. The screen is the same type of thing you find on a TV aerial lead. It doesn't carry any signal but protects the signal from interference from other strong electrical signals such as those that would interfer with a radio signal e.g. when you switch on an electric drill and it makes the TV signal go strange. If you look at the diagram that Gryphon posted earlier, you can see that the screen is connected to earth at one end and pin 3 at the other. It's good that this connection shows continuity but doesn't really help if the signal itself is not making a good connection. The signal is on pins 1 and 2 on the connector. If you look at the other end of the wiring diagram you can see that those should be connected to pins 8 and 27 respectively on the DME. The only way to check that is to check continuity between pin 1 and pin 8 and then pin 2 and pin 27. I'm not sure where the DME is in your car but I suspect your multimeter leads won't stretch that far. I have two suggestions, either: 1) Now that you know what should be connected to pin 3 you can change the connector over. I strongly suggest you make a sketch and label as many parts as possible before you take it all apart. Also take photgraphs. You need to make sure that pins 1 and 2 are in the correct positions when you put the new connector on. 2) Contact an auto electrician who will be able to check the connections for you and can then change over the connector as necessary. I hope you get it sorted but please don't be afraid to admit when you need professional help. Good luck with it. |
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| Author: | Gryphon [ Thu Aug 09, 2018 1:08 pm ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
To echo Matt and Waylander above, finding the ground on pin three was simply to identify the pin numbers on the connector. It is just shielding, not a signal wire. Your DME should be under the steering column in the cabin in a 924S I believe - you could unplug that and check continuity from the other pins to the DME connector but would need to extend your multimeter leads with some bits of wire. I was under the impression that you'd already confirmed there was a bad connection or internal brake in that area and were going to replace the connector. If you're not confident bringing in an auto electrician may not be a bad shout. |
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| Author: | j.c [ Thu Aug 09, 2018 1:52 pm ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
In my experience you get a far better idea about the electrical integrity of a circuit by using the Ohms setting (set to 200Ω) also this will avoid any false continuity results due to diodes. Measure across the leads, remember it, then measure the circuit, a reading of less than 0.3Ω (above the lead value) is fine |
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| Author: | mikseymono [ Thu Aug 09, 2018 3:17 pm ] |
| Post subject: | Re: Hits wall at 4000 rpm/limited performance - ref sensors? |
Gryphon wrote: To echo Matt and Waylander above, finding the ground on pin three was simply to identify the pin numbers on the connector. It is just shielding, not a signal wire. Your DME should be under the steering column in the cabin in a 924S I believe - you could unplug that and check continuity from the other pins to the DME connector but would need to extend your multimeter leads with some bits of wire. I was under the impression that you'd already confirmed there was a bad connection or internal brake in that area and were going to replace the connector. If you're not confident bringing in an auto electrician may not be a bad shout. Thanks for this....I did extend my multimeter wires and checked from the DME back to the female plug...and all checked out. Wierd thing is I can't replicate the intermitent sensor fault now!.. For the moment I am waiting a new alternator regulator as old brushes are really short and hope this will fix my low rev charging issue (only charges battery when reved to 3000rpm or above)... Oh the joys...  M |
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