Ever since the purchase of my '89 Cheyenne, I've had shifting problems (recently rectified w/TransGo 700 kit) and my speedometer hasn't worked. I've replaced the cluster twice and still no speedo. While the cluster was out, I disconnected the harness from the VSS and tested the wiring from the sensor to the cluster. Good continuity. With the cluster still out, I reconnected the harness to the VSS, started the truck, put it in gear (truck still on Jack stands} and got a signal at the at the cluster connector. Backing up a bit to the install of the 700 kit, I noticed the TV cable didn't seem right. Also, there was a bracket on the pan for a shifter cable. Anyways, back to the VSS. The GM shop manual says the resistance of the VSS should be 900-2000 ohms. I got 400 ohms. So, thinking I had a bad VSS, I purchased a new one. When I had it, I pulled out the VSS from the trans. It was entirely different from the one purchased. It was gear driven, not a pulse generator style that should have been in there. Come to find out, the trans is from a car. The output is 2000 pulses per mile whereas the truck is looking for a 4000 pm signal. Now my dilema or question is this. Does anyone have a trashed 700r4 that would be willing to take the tail shaft housing off and remove the VSS drive components and sell them to me? I don't really want to have to replace the entire transmission from a boneyard, just to get the need components. Thanks
7004R VSS situation
- Thread starter Leeztruk
- Start date
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After some more research, looks like the reluctor wheel is inexpensive to buy new. Also, my extension housing will need to be changed, as the one I have mounts the VSS in the wrong position. So I will be replacing that as well. Just need to find out exactly where on the output shaft that the reluctor needs to be placed
No, it's ~2000 PPM depending on rear gears and tires. Here's my 88 700R4 with EBL Flash-II
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IIRC, it goes just behind the 2 little holes in the shaft.
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You're correct on the 2000ppm. Went back to the shop manual and verified this. Thanks for the general info and where to place the reluctor. Mayhap it's the 4L60E that is 4000ppm? I remember those numbers from somewhere
Yeah, I think it was 95+ that went to 4K PPM but, not sure.
I had a failed cluster on my '88. Changed speedo, no improvement. Changed the cluster using the original speedo, and it worked.
How do you know your replacement clusters are good? How do you know your speedo(s) have been good?
How do you know your replacement clusters are good? How do you know your speedo(s) have been good?
After changing the cluster twice as well as using a known good speedometer head, the odds are better than even that a problem lies elsewhere. I've got a reluctor wheel and truck extension housing coming, so we'll see if that cures the problem. Everything else in both clusters work.
Here's a follow-up on the VSS/Speedo situation: Got the reluctor wheel installed this morning. A straight forward job (with the right components; see pics) With a can of freeze spray, I chilled the output shaft, heated the wheel with a Mapp gas torch, and the wheel literally slid to just about the correct spot where the wheel is centered in the sensor hole. With a few judicious raps with the 4lb. hammer and a cut-off section of a '48 Willys steering column (left over from a previous build) the wheel was nudged on the shaft so that the rear-most hole in the shaft was showing. After re-assembling everything, the truck was started and put into drive(rear still off the ground), and taadaah, I now have a working speedometer in my truck
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After all is said and done, comparing the car housing to the truck housing, I could have used the car housing and not have incurred the expense of buying a truck housing. On the plus side though, the rebuilt truck housing has a new bushing installed, as well as a new yoke seal and mating gasket. The only difference I could see is the mounting bosses for the torque arm for the car
