1987 Dodge Dakota height sensing proportiong valve

Tiny
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I wonder if Dusty or Alxxl are still around to give an update on how their bybass is working?

I tried to work this out about 5 years ago. I talked to mechanics, service managers and engineers and they all said I would be crazy to try it. Glad you figured it out. Now I have no choice because the lines have corroded and split and the valve is a mass of rust.

So help me get this straight:
1. You block off the back port which goes straight (in-line) with the front proportioning valve. How did you do that because that is a wacky looking fitting! (Large nut with small tube opening) Where did you find a plug?
2. Then you run the line which branches off the bottom of that same front proportioning valve and route that back to the Tee on the rear axle.
3. The line that used to come off the rear of the front proportioning valve to the HSPV is completely eliminated.

Is that it? I wonder what that other (bypass?) Line was for?
Hope you guys are out there.
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Wednesday, March 4th, 2009 AT 5:06 PM
Tiny
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I thought I would add to the success list for anybody researching this problem. I bypassed the height sensing valve just the way it was described by Dusty and Axxl and it seems to work great. Rear wheels locked up a couple of times during a rapid stop when the roads were wet. But all-in-all it was a good way to eliminate this annoying and expensive problem for just a couple of bucks (brake line and brake fluid fluid).
Thanks guys.
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Sunday, March 8th, 2009 AT 7:01 PM
Tiny
MERLIN2021
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OK, Your welcome.
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Monday, March 9th, 2009 AT 11:27 AM
Tiny
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Great posts guys. Ends up I have the same problem as well. I have an old 87 Dodge Dakota that I am working to get back on the road. I did the HSPV Bypass and blocked off the return on the main proportional valve. Everything seems to work great and have decent pressure in the brakes but I still have the brake light on my dash. Now is this light on the dash related or is this pointing to another issue. My thing is I am trying to get a NYS Inspection done but need to get the light to go off. Any ideas on what it could be, is it because of the HSPV bypass, or is it something else. What would cause this light to trigger?
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Monday, July 20th, 2009 AT 7:46 AM
Tiny
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If it's the red light check the parking brak lever, the switch there may be stuck/defective, or you actually are low on fluid or have a leak still.
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Monday, July 20th, 2009 AT 1:10 PM
Tiny
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[quote="merlin2021"]If it's the red light check the parking brak lever, the switch there may be stuck/defective, or you actually are low on fluid or have a leak still.[/Quote

Yup it's the red brake light on the dash. For the longest time it was the parking brake lever that was messing up. It no has been on constantly. I even tried disconnecting the parking brake sensor wire to see that would get the light to go out and it didn't change anything. Now would doing the HSPV bypass and plugging the return line on the main proportional valve cause the light to go on?
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Monday, July 20th, 2009 AT 2:15 PM
Tiny
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Let me ask you this, was the light off before you did the valve bypass? If yes, I would say you may have something to recheck. The combination valve that you ran the line from, does it have an electrical connection to it? If so, try opening a front bleeder, and pressing down on the pedal, close the bleeder, and step on the brake, does the light shut off now? It's an off centerd valve. Recenter it using this method. Then again, if your hieght sensor was leaking fluid and you ran the master dry, you may just need to bleed more air out!
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Monday, July 20th, 2009 AT 2:29 PM
Tiny
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Yes the light was on before I ran the bypass. I bleed both back drums but did not bleed the front and yes the proportional valve does have wires connecting to it at the top. Could the light be going on cause air could be in front half of the system? If I bleed the fronts do I need to bleed the rears again?
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Monday, July 20th, 2009 AT 3:03 PM
Tiny
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If all air was removed from the rear, bleed just the front. Good pressure at rear?
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Monday, July 20th, 2009 AT 3:35 PM
Tiny
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Yeah they actually work now. If I jam on the brakes the back can lock up. I'm going to head home and try bleeding the front to see if it is as simple as that.
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Monday, July 20th, 2009 AT 5:02 PM
Tiny
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Well I went to bleed the fronts and the left one bleed fine but the bleeder valve on the right snapped right off. So for now I cant bleed the right one. Either way it didn't turn the light off. I tried doing the reset procedure by holding down the brake pedal with the Ignition turned to AC and that didn't work. In the end I just went to the proportional valve and removed the sensor wire. That turned the light off. Hopefully that will get me through inspection.

As for later I still have an issue, correct me if I am wrong but either the proportional valve/metering sensor is not working correctly and needs to be replaced, air could still be in the system, or I have a short in the sensor wire going to the brake light. Any other ideas on what it is. Also thanks for the advise thus far all good stuff.
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Monday, July 20th, 2009 AT 7:54 PM
Tiny
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I did ask if the pressure to the rear brakes is good? You might need to use the other line out to the rear. Block the one you are using. You can still blleed the caliper by removing it from the mount, put a block of wood in between the pads, turning it so the banjo bolt the hose attaches with is at the top, and crack it open. Remeber air rises to the top!
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Tuesday, July 21st, 2009 AT 2:51 AM
Tiny
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No the rear brakes do have good pressure now. Yeah I didn't think about bleeding from the banjo bolt very good point. I'll give the system another full bleed to see if it's still got air in it. For the rear port in the back of the proportional valve the one I blocked was the return. This truck is old and needs alot of work. Heck of a project that I decided to take on haha.
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Tuesday, July 21st, 2009 AT 6:14 AM
Tiny
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As long as the brakes hold! If light is out at inspection station, I doubt they will inspect the wiring!
SERVICING METERING VALVE 1. On disc brake equipped vehicles, the metering section of combination valve must be held open before pressure bleeding. 2. Hold metering valve open while pressure bleeding front brakes. To loosen front mounting bolt and install pressure bleeding tool on combination valve, valve stem should be fully extended or depressed. NOTE: Never reintroduce brake fluid that has been drained from hydraulic brake system or that has been allowed to stand in an open container for an extended period of time. Also, do not use fluid that contains a petroleum base. Petroleum based fluids will cause swelling and distortion of rubber parts in hydraulic system. Even if you didnt use a pressure bleeder, it might be worth a shot to hold the valve open while bleeding the fronts.
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Tuesday, July 21st, 2009 AT 3:57 PM
Tiny
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Since I removed the HSPV everything has been fine but I was thinking or replacing or upgrading the main proportioning valve. Does anyone know where I can get one that is compatible with the 1987 Dodge Dakota or would I be able to utilize an aftermarket proportioning valve? I am just airing on the side of caution and would like to pretty much rebuild my brake system in the car.
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Friday, September 4th, 2009 AT 7:46 PM
Tiny
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I always say if it aint broke, dont fix it. That's just me. But get a valve for a cysler van or car that dosent have the HSPV and the lines should match up.
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Saturday, September 5th, 2009 AT 6:57 AM
Tiny
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So basically I can just swap one in that is for a car with front disk and rear drums without a HSPV. Didn't know if you had to get a specfic sized valve or if you could just swap one out. Problem I'm having is the rear plug I am using is leaking ever so slightly. The brakes work but still feel a bit soft just trying to firm them up some more.
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Saturday, September 5th, 2009 AT 8:24 AM
Tiny
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Remove the leaking piece, plug with a rubber plug so you don't loose all your fluid, or press the brake pedal down a feww inches ant hold with a rod and clamp at the steering wheel, this will put the MC piston past the ports and stop all leaking, then take that piece to the parts store and buy a brass plug and use the brass plug! This will eleiminte the problem at a fraction of the cost!
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Saturday, September 5th, 2009 AT 8:49 AM

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