MoparManiac
NAXJA Forum User
- Location
- Amherst, NH
Sweet. Hurry up, wheeling season is right around the corner.
the gm 2 wire sensor generates it's own ac voltage. i would ASSume the jeep 3 wire is a hall effect switch but i could be wrong. i do know it has voltage coming into it. not sure how well that is going to jive together.
That dakota digital unit i linked will convert it to the right signal for you from either an early 2 wire sensor or 3 wire sensor.
Hmm. You're going exactly the other way from me on a recent project I've been working on.
The stock XJ/MJ sender (the 3 pin one) is 8 pulses per revolution of the sender shaft, which with a proper speedo gear (supposed to aim for 1000 revs per mile) means 8000 revs per mile. I don't know what the chevy ECU wants but I'm surprised a stock chevy sender won't fit into the case, aren't they almost all the same on 231J/231D/231C?
If the Chevy ECU wants a coil+magnet style pickup you might try a 91-?? (I want to say 93, but am unsure) Jeep VSS sender, which is a 2 wire coil + mag pickup. I don't know how pulses per rev compare with the early HO sender vs the chevy sender unfortunately.
In my case, it's a 99XJ NP231 in an 87 YJ with an 86 CJ dashboard and mechanical speedo in it that I'm building up for a friend. So I threw in a mechanical speedo sender from a 90-earlier XJ/MJ and connected the mechanical speedo cable to it. Everything works, except it bogs and tries to stall when you clutch in to downshift at speed because it thinks the vehicle isn't moving. Since there's already a speedo gear drive in the case there's no space for another to make the ECU happy... I am investigating using the 87 YJ cruise control speed sensor halfway up the speedo drive cable, unsure if it's a reed switch or mag+coil pickup nor how many pulses/rev it outputs at this point but a little playing with an oscilloscope and a DMM should straighten it out fairly quick.
Hopefully this helps or gives you some ideas.
pretty sure the 91-? 2 wire sensors are of the reed switch variety. i have a 91 and not a single mag/coil sensor would work with it. i use the open/closed output on the dakota digital sgi-5 and it works fine, the ac output does not.
Interesting. I checked my 91 FSM a few weeks ago while working on this and it showed a coil pickup same as the ABS sensors, maybe I'm just wrong.
Worth noting is that I just checked my 93 FSM and 93s apparently have the 3 pin version, so the 2 pin reed (or coil pickup, but I'm probably wrong) version is 91 and possibly 92. Can't find my 92 FSM right now, probably at the shop.
one thing i did notice is that if i touch the speedo wires together quickly the speedo moves. the white/orange (?) wire is +5v when checked with my volt meter. i know 91-92 or 93 is sort of a bastard year for the speedo sensor (long shaft + electronic) so maybe its a little different. it was open/closed approximately 3 times per rev of the driveshaft when checked with an ohm meter. i believe its a 39t gear.
i would have gone 12" and saved some money and had less unloading.
if i had to guess, the xj goes away from the reed style switch when the speedo gear changes from a long shaft to a short shaft, i think in 93. i know the speedo sensor in my 94 zj was not a reed switch.Just gonna lay this all to rest. I needed a test guinea pig on Tuesday for a signal converter board I prototyped for that 87 YJ project. I had the 91 MJ sender on my bench since the transfer case was in pieces, so I tried it first to avoid going outside. The 91 MJ sender is definitely a reed switch sender like Vanimal said. 8 pulses per rev as usual.
I don't know what the 92/93/94 senders are, but they're probably reed switch and hall effect types, depending on year.
The 87 YJ cruise control sender is definitely a variable reluctance / coil pickup type, it produces an AC signal.
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arty:
When are we going to see the MJ out on the trail?