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bypassing starter relay on late gm

posted May 08, 2016 22:03:11 by tony redolfi
well I jumped relay points 87 and 30, all I get is a click from the starter, it wont crank.

the car is in 100% working order, I just wanted to test my new jump switch out..

I'm guessing this has something to do with the anti theft?

btw this is on a 2013 equinox
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21 replies
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Tyler said May 08, 2016 23:29:18
Yep, you guessed it, incoming wiring diagram! Not that you don't know how a relay works, just for anyone following along:



To be honest, I don't see anything here that would explain why the engine isn't cranking. There's an anti-theft system, sure, but you've taken it out of the equation by jumping the relay.

No offense meant here, but are you sure there isn't a voltage drop in your jump switch? Maybe get a voltage reading at pin 87 or F9 with the jump switch closed, solenoid clicked.
[Last edited May 08, 2016 23:29:55]
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Noah said May 08, 2016 23:44:07
Yeah, if you're jumping 30 and 87 it should crank. I think Tyler is right on with the voltage measurement on F9 with the switch closed.

Did you make a relay bypass? I've made a few in the past out of relays from the junk yard and had little success soldering anything to the relay pins, and anything that did stick wouldn't fit with the cover back on the relay.
Massachusetts, USA
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tony redolfi said May 09, 2016 00:34:39
I took the switch out of the picture,,, just used a jumper wire and nothing but a click, in fact I used 3 different methods of jumping them... all I get is a click

I tried it with the key on and jumped,,, just a click

I put the relay back in turn the key to start and it fires right up

also,, just tried a 4th jumper wire I had and it also just clicked.


yup
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tony redolfi said May 09, 2016 00:45:07
sorry, I didn't read that last part you wrote noah

what I used is a set of hantek breakout leads, I can even keep the relay hooked up while testing. I got them off ebay for 40 bucks, they fit everything and have banana test ports


I just hooked my cheapo HF switch to the test ports


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tony redolfi said May 09, 2016 01:56:23
hahahahaha I was hooked up to the wrong relay,,, theres something called a (run-crank) so not really thinking all too hard or continue to read the relay chart until I seen the one marked starter


oh well,, hope you all had a good laugh at me,,, what the hell does a run-crank relay do,,, I guess Ill go google that one,, but it sounds just like the starter sil in that area


heres some pictures of that hantek breakout used with my switch

as not to make this thread a complete waste of everyones time lol!



[Last edited May 09, 2016 01:56:52]
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Tyler said May 09, 2016 02:01:13
I took the switch out of the picture,,, just used a jumper wire and nothing but a click, in fact I used 3 different methods of jumping them... all I get is a click

I tried it with the key on and jumped,,, just a click

I put the relay back in turn the key to start and it fires right up

also,, just tried a 4th jumper wire I had and it also just clicked.


yup


Ummmmmm... WTF? Either the diagram is wrong, or I'm missing something obvious.

If you have the time, would you mind getting voltage readings at the starter? At B+ and the solenoid control?

I know that you were using this as a test for your jump switch, but I'm really curious now!
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Tyler said May 09, 2016 02:12:45
hahahahaha I was hooked up to the wrong relay,,, theres something called a (run-crank) so not really thinking all too hard or continue to read the relay chart until I seen the one marked starter


Ahahaha, wow, that's actually a relief to hear! I was staring at the diagram, wondering what could possibly be going wrong. Started to doubt myself, lol.

oh well,, hope you all had a good laugh at me,,, what the hell does a run-crank relay do,,, I guess Ill go google that one,, but it sounds just like the starter sil in that area


Nah, I can't laugh at that. Last week, I had the coolant drained out of this Nissan to change radiator hoses. Got the vacuum filler set up to fill the system, kept trying to draw a vacuum, wouldn't draw down past 1"hg. Left the drain petcock out of the radiator. Oops!

But seriously, I do wonder what you were hearing clicking. I'll have a glance at that diagram later.

I DO like the look of those leads, though. Are these the same thing? I've got a set of the Hantek backprobes, and they've treated me well.
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tony redolfi said May 09, 2016 02:24:37
yup those are the same, I wonder how I ever lived without them, just for relays they are better compared to that 200buck relay jump kit,,,because those jumper boxes wont fit into every area,,, but these leads fit everywhere and everything.

and i love the banana jack test ports,,, i just ordered a set of banana plugs to replace the gator clips on that starter switch
[Last edited May 09, 2016 02:25:20]
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Noah said May 09, 2016 02:33:30
According to AllData, the run/crank relay is the ignition main relay. Honest mistake man, don't get too down on yourself about it. I can see how a quick glance at the cover could mess you up on this one!

That's a pretty cool set of break out test leads. Do you have any concern about running the starter solenoid current through the banana jack test connectors? I only ask because I've melted back probes trying to energize power seat motors and such.
Massachusetts, USA
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tony redolfi said May 09, 2016 02:51:48
naa, they didn't get hot or anything, plus you get more contact with a banana compared to a needle point,, the wire terminals on the ends are the same ones as the components,, and the wires are on the heavy side.

not saying you cant melt them,,, but they didn't heat up or anything during my cranking tests. worked very well

like I said I got my set on ebay from china, it took 3weeks but I only paid 40bucks
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tony redolfi said May 09, 2016 03:12:45
hey there is one thing id like to know while on this topic,, on this 2013 gm,, in the fuse box under the hood there are these "test points"

on my cover it says things like

71- test point (228A)

and it goes from 71 to 76,, I looked over pages of wiring diagrams trying to find one of these test points.


I gotta know what these things do,, probably turn on fuel pumps and stuff for bypass testing?


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Noah said May 09, 2016 12:15:59
I think that's exactly what they are for. I know I've seen older GM vehicles with relay bypass pins next to the respective relays. So you can run the fuel pump and such.
Massachusetts, USA
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Noah said May 10, 2016 03:26:21
In this video about an Astro with low fuel pressure at about 7min 30sec, ScannerDanner jumps battery voltage to the GM fuel pump test connector under the hood to energize the fuel pump.
I don't know if you have a premium channel subscription, this video is on the free channel.

The one on the Astro is a loose wire with a female terminal, but I believe it's the same as the cavity you see next to the relay in the underhood fuse box.
[Last edited May 10, 2016 03:26:58]
Massachusetts, USA
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tony redolfi said May 10, 2016 15:37:13
ok I tried some tests based on the points being near other components, nothing yet

for example the test point 74 (6128) is near the fuse 32 that is the power trunk motor. (would make sense to have a test point on that)


I don't know if its that or something else as its in the middle of 4 things..

I wish I could find some documentation about these points,, a wiring diagram anything, why keep this info some big dealership secret

ill keep at it, hopefully Ill figure it out
[Last edited May 10, 2016 15:39:56]
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Noah said May 10, 2016 22:32:31
I'll check some diagrams after dinner and see if I can find something useful. Did you take a voltage measurement on any of the pins just to see what's going on?
Massachusetts, USA
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